Enforce compilation without system headers

This patch introduces HOST_CPPFLAGS to be used for all
objects being compiled with HOSTCC rather then the target
compiler.

Since glibc is not linked into the EC, no glibc include files
should be included in the EC code base. Hence, create local
definitions for clock_t and wchar_t that match what the glibc
include would have done, and remove some unneeded includes.

Due to very eager optimization, we have to give gcc a little
notch to not kick out memset.

Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
BUG=chrome-os-partner:43025
BUG=chrome-os-partner:49517
BRANCH=none
TEST=compile tested

Change-Id: Idf3a2881fa8352756b0927b09c6a97473358f239
Reviewed-on: https://chromium-review.googlesource.com/322435
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Patrick Georgi <pgeorgi@chromium.org>

4 files changed, 7 insertions, 4 deletions

diff --git a/include/compile_time_macros.h b/include/compile_time_macros.h
index 074fb4b256..9b543f9493 100644
--- a/include/compile_time_macros.h
+++ b/include/compile_time_macros.h
@@ -23,4 +23,6 @@
 #define offsetof(type, member)  __builtin_offsetof(type, member)
 #endif
 
+#define __visible	__attribute__((externally_visible))
+
 #endif /* __CROS_EC_COMPILE_TIME_MACROS_H */
diff --git a/include/timer.h b/include/timer.h
index 5f92207252..0e7fd7d7ea 100644
--- a/include/timer.h
+++ b/include/timer.h
@@ -8,8 +8,6 @@
 #ifndef __CROS_EC_TIMER_H
 #define __CROS_EC_TIMER_H
 
-#include <sys/types.h>
-
 #include "common.h"
 #include "task_id.h"
 
@@ -28,6 +26,9 @@ typedef union {
 	} le /* little endian words */;
 } timestamp_t;
 
+/* Data type for POSIX style clock() implementation */
+typedef long clock_t;
+
 /**
  * Initialize the timer module.
  */
diff --git a/include/trng.h b/include/trng.h
index a35496c3fd..e6dcba644c 100644
--- a/include/trng.h
+++ b/include/trng.h
@@ -5,7 +5,7 @@
 #ifndef __EC_INCLUDE_TRNG_H
 #define __EC_INCLUDE_TRNG_H
 
-#include <sys/types.h>
+#include <stddef.h>
 
 /**
  * Initialize the true random number generator.
diff --git a/include/util.h b/include/util.h
index 8fec4a14e8..d8967ec0c0 100644
--- a/include/util.h
+++ b/include/util.h
@@ -95,7 +95,7 @@ int isalpha(int c);
 int isprint(int c);
 int memcmp(const void *s1, const void *s2, size_t len);
 void *memcpy(void *dest, const void *src, size_t len);
-void *memset(void *dest, int c, size_t len);
+__visible void *memset(void *dest, int c, size_t len);
 void *memmove(void *dest, const void *src, size_t len);
 int strcasecmp(const char *s1, const char *s2);
 int strncasecmp(const char *s1, const char *s2, size_t size);