runtime: fix mingw build, implement missing destroylock()

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/747041

diff --git a/src/pkg/runtime/mingw/thread.c b/src/pkg/runtime/mingw/thread.c
index 94ffc27521e9d86bdb2345ab8c752006cb5e2c65..9a0bf2a8a64b3ecacf8dc7c7e71f2f532f69bb0a 100644 (file)
--- a/src/pkg/runtime/mingw/thread.c
+++ b/src/pkg/runtime/mingw/thread.c
@@ -217,6 +217,11 @@ unlock(Lock *l)
        eventunlock(l);
 }
 
+void
+destroylock(Lock *l)
+{
+}
+
 void
 noteclear(Note *n)
 {