runtime: correct various Go -> C function calls

Some things get converted.
Other things (too complex or too many C deps) get onM calls.
Other things (too simple) get #pragma textflag NOSPLIT.

After this CL, the offending function list is basically:
        - panic.c
        - netpoll.goc
        - mem*.c
        - race stuff
        - readgstatus
        - entersyscall/exitsyscall

LGTM=r, iant
R=golang-codereviews, r, iant
CC=dvyukov, golang-codereviews, khr
https://codereview.appspot.com/140930043

1 files changed, 7 insertions, 2 deletions

diff --git a/src/pkg/runtime/debug.go b/src/pkg/runtime/debug.go
index ed11fb1b1..bb4bd60ed 100644
--- a/src/pkg/runtime/debug.go
+++ b/src/pkg/runtime/debug.go
@@ -24,10 +24,15 @@ func UnlockOSThread()
 // The number of logical CPUs on the local machine can be queried with NumCPU.
 // This call will go away when the scheduler improves.
 func GOMAXPROCS(n int) int {
-	return int(gomaxprocsfunc(int32(n)))
+	g := getg()
+	g.m.scalararg[0] = uintptr(n)
+	onM(gomaxprocs_m)
+	n = int(g.m.scalararg[0])
+	g.m.scalararg[0] = 0
+	return n
 }
 
-func gomaxprocsfunc(int32) int32 // proc.c
+func gomaxprocs_m() // proc.c
 
 // NumCPU returns the number of logical CPUs on the local machine.
 func NumCPU() int {