Auto merge of #2636 - skrap:master, r=Amanieu0.2.113

uclibc: fix O_TMPFILE value, hide some unused fields to fix libc-test

This was a bit of a yak-shave.

First, O_TMPFILE was wrong because 020000000 is decimal, not octal.  :facepalm:   This was, of course, causing all sorts of things to be horrible.

That led me to switch to a newer toolchain which actually defined O_TMPFILE, so that the libc tests pass on `armv7-unknown-linux-uclibceabihf`.

That revealed that certain field names had changed since the last time I ran the libc tests on this architecture, which revealed that some struct fields (e.g. `__unused`) were being marked as `pub` where all other architectures left them as private.

So, this patch might seem somewhat sprawling, but without all of these changes it's not possible to run libc-test!

To test:
* get https://toolchains.bootlin.com/downloads/releases/toolchains/armv7-eabihf/tarballs/armv7-eabihf--uclibc--bleeding-edge-2021.11-1.tar.bz2
* unpack somewhere, and call that `$TOOLCHAIN`
```
cd libc-test

PATH=$TOOLCHAIN/bin:$PATH \
  CC_armv7_unknown_linux_uclibc=armv7-buildroot-linux-uclibc-gcc \
  CARGO_TARGET_ARMV7_UNKNOWN_LINUX_UCLIBCEABIHF_LINKER=armv7-buildroot-linux-uclibc-gcc \
  CARGO_TARGET_ARMV7_UNKNOWN_LINUX_UCLIBCEABIHF_RUNNER="qemu-arm -L $TOOLCHAIN/arm-buildroot-linux-uclibcgnueabihf/sysroot/" \
  cargo +nightly test --target armv7-unknown-linux-uclibceabihf -Zbuild-std=core,std
```

4 files changed, 21 insertions, 31 deletions

diff --git a/ci/docker/armv7-unknown-linux-uclibceabihf/Dockerfile b/ci/docker/armv7-unknown-linux-uclibceabihf/Dockerfile
index f868f65573..c328a6a913 100644
--- a/ci/docker/armv7-unknown-linux-uclibceabihf/Dockerfile
+++ b/ci/docker/armv7-unknown-linux-uclibceabihf/Dockerfile
@@ -6,7 +6,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 RUN mkdir /toolchain
 
-RUN curl --retry 5 -L https://toolchains.bootlin.com/downloads/releases/toolchains/armv7-eabihf/tarballs/armv7-eabihf--uclibc--bleeding-edge-2020.08-1.tar.bz2 | \
+RUN curl --retry 5 -L https://toolchains.bootlin.com/downloads/releases/toolchains/armv7-eabihf/tarballs/armv7-eabihf--uclibc--bleeding-edge-2021.11-1.tar.bz2 | \
     tar xjf - -C /toolchain --strip-components=1
 RUN /toolchain/relocate-sdk.sh
 
diff --git a/libc-test/build.rs b/libc-test/build.rs
index a3e52fa145..8ceae3d99d 100644
--- a/libc-test/build.rs
+++ b/libc-test/build.rs
@@ -3167,10 +3167,6 @@ fn test_linux(target: &str) {
             "NETLINK_GET_STRICT_CHK" if arm || mips || musl => true,
 
             // kernel constants not available in uclibc 1.0.34
-            | "ADDR_COMPAT_LAYOUT"
-            | "ADDR_LIMIT_3GB"
-            | "ADDR_NO_RANDOMIZE"
-            | "CLONE_NEWCGROUP"
             | "EXTPROC"
             | "FAN_MARK_FILESYSTEM"
             | "FAN_MARK_INODE"
@@ -3181,13 +3177,7 @@ fn test_linux(target: &str) {
             | "IPV6_PMTUDISC_INTERFACE"
             | "IPV6_PMTUDISC_OMIT"
             | "IPV6_ROUTER_ALERT_ISOLATE"
-            | "O_TMPFILE"
             | "PACKET_MR_UNICAST"
-            | "PTRACE_EVENT_STOP"
-            | "PTRACE_O_EXITKILL"
-            | "PTRACE_O_SUSPEND_SECCOMP"
-            | "PTRACE_PEEKSIGINFO"
-            | "READ_IMPLIES_EXEC"
             | "RUSAGE_THREAD"
             | "SHM_EXEC"
             | "UDP_GRO"
diff --git a/src/unix/linux_like/linux/uclibc/arm/mod.rs b/src/unix/linux_like/linux/uclibc/arm/mod.rs
index dc84b0c054..c1008a48f6 100644
--- a/src/unix/linux_like/linux/uclibc/arm/mod.rs
+++ b/src/unix/linux_like/linux/uclibc/arm/mod.rs
@@ -44,14 +44,14 @@ s! {
 
     pub struct stat {
         pub st_dev: ::c_ulonglong,
-        pub __pad1: ::c_ushort,
+        __pad1: ::c_ushort,
         pub st_ino: ::ino_t,
         pub st_mode: ::mode_t,
         pub st_nlink: ::nlink_t,
         pub st_uid: ::uid_t,
         pub st_gid: ::gid_t,
         pub st_rdev: ::c_ulonglong,
-        pub __pad2: ::c_ushort,
+        __pad2: ::c_ushort,
         pub st_size: ::off_t,
         pub st_blksize: ::blksize_t,
         pub st_blocks: ::blkcnt_t,
@@ -61,8 +61,8 @@ s! {
         pub st_mtime_nsec: ::c_long,
         pub st_ctime: ::time_t,
         pub st_ctime_nsec: ::c_long,
-        pub __unused4: ::c_ulong,
-        pub __unused5: ::c_ulong,
+        __unused4: ::c_ulong,
+        __unused5: ::c_ulong,
     }
 
     pub struct stat64
@@ -202,44 +202,44 @@ s! {
         pub cuid: ::uid_t,
         pub cgid: ::gid_t,
         pub mode: ::c_ushort,
-        pub __pad1: ::c_ushort,
+        __pad1: ::c_ushort,
         pub __seq: ::c_ushort,
-        pub __pad2: ::c_ushort,
-        pub __unused1: ::c_ulong,
-        pub __unused2: ::c_ulong,
+        __pad2: ::c_ushort,
+        __unused1: ::c_ulong,
+        __unused2: ::c_ulong,
     }
 
     pub struct msqid_ds {
         pub msg_perm: ::ipc_perm,
         pub msg_stime: ::time_t,
-        pub __unused1: ::c_ulong,
+        __unused1: ::c_ulong,
         pub msg_rtime: ::time_t,
-        pub __unused2: ::c_ulong,
+        __unused2: ::c_ulong,
         pub msg_ctime: ::time_t,
-        pub __unused3: ::c_ulong,
-        pub __msg_cbytes: ::c_ulong,
+        __unused3: ::c_ulong,
+        __msg_cbytes: ::c_ulong,
         pub msg_qnum: ::msgqnum_t,
         pub msg_qbytes: ::msglen_t,
         pub msg_lspid: ::pid_t,
         pub msg_lrpid: ::pid_t,
-        pub __unused4: ::c_ulong,
-        pub __unused5: ::c_ulong,
+        __unused4: ::c_ulong,
+        __unused5: ::c_ulong,
     }
 
     pub struct shmid_ds {
         pub shm_perm: ::ipc_perm,
         pub shm_segsz: ::size_t,
         pub shm_atime: ::time_t,
-        pub __unused1: ::c_ulong,
+        __unused1: ::c_ulong,
         pub shm_dtime: ::time_t,
-        pub __unused2: ::c_ulong,
+        __unused2: ::c_ulong,
         pub shm_ctime: ::time_t,
-        pub __unused3: ::c_ulong,
+        __unused3: ::c_ulong,
         pub shm_cpid: ::pid_t,
         pub shm_lpid: ::pid_t,
         pub shm_nattch: ::shmatt_t,
-        pub __unused4: ::c_ulong,
-        pub __unused5: ::c_ulong,
+        __unused4: ::c_ulong,
+        __unused5: ::c_ulong,
     }
 }
 
diff --git a/src/unix/linux_like/linux/uclibc/mod.rs b/src/unix/linux_like/linux/uclibc/mod.rs
index e25a6bfb48..8f23826f29 100644
--- a/src/unix/linux_like/linux/uclibc/mod.rs
+++ b/src/unix/linux_like/linux/uclibc/mod.rs
@@ -303,7 +303,7 @@ pub const MAP_HUGE_16GB: ::c_int = 34 << MAP_HUGE_SHIFT;
 pub const MINSIGSTKSZ: ::c_int = 2048;
 pub const MSG_COPY: ::c_int = 040000;
 pub const NI_MAXHOST: ::socklen_t = 1025;
-pub const O_TMPFILE: ::c_int = 020000000 | O_DIRECTORY;
+pub const O_TMPFILE: ::c_int = 0o20000000 | O_DIRECTORY;
 pub const PACKET_MR_UNICAST: ::c_int = 3;
 pub const PF_NFC: ::c_int = 39;
 pub const PF_VSOCK: ::c_int = 40;