runtime: correct '.' to '·' in comments

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5495097

src/pkg/runtime/lock_futex.c

@@ -8,13 +8,13 @@
 
 // This implementation depends on OS-specific implementations of
 //
-//	runtime.futexsleep(uint32 *addr, uint32 val, int64 ns)
+//	runtime·futexsleep(uint32 *addr, uint32 val, int64 ns)
 //		Atomically,
 //			if(*addr == val) sleep
 //		Might be woken up spuriously; that's allowed.
 //		Don't sleep longer than ns; ns < 0 means forever.
 //
-//	runtime.futexwakeup(uint32 *addr, uint32 cnt)
+//	runtime·futexwakeup(uint32 *addr, uint32 cnt)
 //		If any procs are sleeping on addr, wake up at most cnt.
 
 enum

src/pkg/runtime/lock_sema.c

@@ -8,17 +8,17 @@
 
 // This implementation depends on OS-specific implementations of
 //
-//	uintptr runtime.semacreate(void)
+//	uintptr runtime·semacreate(void)
 //		Create a semaphore, which will be assigned to m->waitsema.
 //		The zero value is treated as absence of any semaphore,
 //		so be sure to return a non-zero value.
 //
-//	int32 runtime.semasleep(int64 ns)
+//	int32 runtime·semasleep(int64 ns)
 //		If ns < 0, acquire m->waitsema and return 0.
 //		If ns >= 0, try to acquire m->waitsema for at most ns nanoseconds.
 //		Return 0 if the semaphore was acquired, -1 if interrupted or timed out.
 //
-//	int32 runtime.semawakeup(M *mp)
+//	int32 runtime·semawakeup(M *mp)
 //		Wake up mp, which is or will soon be sleeping on mp->waitsema.
 //