compiler, runtime: add layout parameter to runtime.alloc

This layout parameter is currently always nil and ignored, but will
eventually contain a pointer to a memory layout.

This commit also adds module verification to the transform tests, as I
found out that it didn't (and therefore didn't initially catch all
bugs).

src/runtime/chan.go

@@ -133,7 +133,7 @@ func chanMake(elementSize uintptr, bufSize uintptr) *channel {
 	return &channel{
 		elementSize: elementSize,
 		bufSize:     bufSize,
-		buf:         alloc(elementSize * bufSize),
+		buf:         alloc(elementSize*bufSize, nil),
 	}
 }