runtime: split minit() to mpreinit() and minit()
mpreinit() is called on the parent thread and with mcache (can allocate memory),
minit() is called on the child thread and can not allocate memory.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/7389043
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 8162874..4ca7cc7 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -660,6 +660,7 @@
void runtime·newosproc(M *mp, G *gp, void *stk, void (*fn)(void));
G* runtime·malg(int32);
void runtime·asminit(void);
+void runtime·mpreinit(M*);
void runtime·minit(void);
void runtime·unminit(void);
void runtime·signalstack(byte*, int32);
