build: a round of fixes

TBR=r
CC=golang-dev
https://golang.org/cl/5503052
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 7ab7a3f..7f1cb59 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -635,7 +635,8 @@
  * low level C-called
  */
 uint8*	runtime·mmap(byte*, uintptr, int32, int32, int32, uint32);
-void	runtime·munmap(uint8*, uintptr);
+void	runtime·munmap(byte*, uintptr);
+void	runtime·madvise(byte*, uintptr, int32);
 void	runtime·memclr(byte*, uintptr);
 void	runtime·setcallerpc(void*, void*);
 void*	runtime·getcallerpc(void*);