runtime: convert memclrBytes to Go

LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/131980043

src/pkg/runtime/alg.go

@@ -273,3 +273,9 @@ func ifaceHash(i interface {
 }, seed uintptr) uintptr {
 	return goalg(&algarray[alg_INTER]).hash(noescape(unsafe.Pointer(&i)), unsafe.Sizeof(i), seed)
 }
+
+// Testing adapter for memclr
+func memclrBytes(b []byte) {
+	s := (*sliceStruct)(unsafe.Pointer(&b))
+	memclr(s.array, uintptr(s.len))
+}

src/pkg/runtime/alg.goc

@@ -287,8 +287,3 @@ runtime·hashinit(void)
 		}
 	}
 }
-
-// Testing adapter for memclr
-func memclrBytes(s Slice) {
-	runtime·memclr(s.array, s.len);
-}

src/pkg/runtime/export_test.go

@@ -78,13 +78,10 @@ var Int32Hash = int32Hash
 var Int64Hash = int64Hash
 var EfaceHash = efaceHash
 var IfaceHash = ifaceHash
+var MemclrBytes = memclrBytes
 
 var HashLoad = &hashLoad
 
-func memclrBytes(b []byte)
-
-var MemclrBytes = memclrBytes
-
 func gogoBytes() int32
 
 var GogoBytes = gogoBytes