runtime/cgo: adapt files copied from libcgo

Necessary but not sufficient step toward
making those builds work.

R=r
CC=golang-dev
https://golang.org/cl/3411043

src/pkg/runtime/cgo/freebsd_386.c

@@ -11,14 +11,11 @@ char *environ[] = { 0 };
 char *__progname;
 
 static void
-inittls(void)
+xinitcgo(void)
 {
 }
 
-void
-initcgo(void)
-{
-}
+void (*initcgo)(void) = xinitcgo;
 
 void
 libcgo_sys_thread_start(ThreadStart *ts)

src/pkg/runtime/cgo/freebsd_amd64.c

@@ -10,11 +10,13 @@ static void* threadentry(void*);
 char *environ[] = { 0 };
 char *__progname;
 
-void
-initcgo(void)
+static void
+xinitcgo(void)
 {
 }
 
+void (*initcgo)(void) = xinitcgo;
+
 void
 libcgo_sys_thread_start(ThreadStart *ts)
 {

src/pkg/runtime/cgo/nacl_386.c

@@ -4,11 +4,13 @@
 
 #include "libcgo.h"
 
-void
-initcgo(void)
+static void
+xinitcgo(void)
 {
 }
 
+void (*initcgo)(void) = xinitcgo;
+
 void
 libcgo_sys_thread_start(ThreadStart *ts)
 {

src/pkg/runtime/cgo/windows_386.c

@@ -12,11 +12,13 @@ static void *threadentry(void*);
    Allocation granularity on Windows is typically 64 KB. */
 #define STACKSIZE (1*1024*1024)
 
-void
-initcgo(void)
+static void
+xinitcgo(void)
 {
 }
 
+void (*initcgo)(void) = xinitcgo;
+
 void
 libcgo_sys_thread_start(ThreadStart *ts)
 {

src/pkg/runtime/cgo/windows_amd64.c

@@ -12,11 +12,13 @@ static void *threadentry(void*);
    Allocation granularity on Windows is typically 64 KB. */
 #define STACKSIZE (2*1024*1024)
 
-void
-initcgo(void)
+static void
+xinitcgo(void)
 {
 }
 
+void (*initcgo)(void) = xinitcgo;
+
 void
 libcgo_sys_thread_start(ThreadStart *ts)
 {