mesa: init tmpNode to zeros

src/mesa/shader/slang/slang_emit.c

@@ -727,6 +727,7 @@ emit_clamp(slang_emit_info *emitInfo, slang_ir_node *n)
     * dest for this clamp() is an output reg, we can't use that reg for
     * the intermediate result.  Use a temp register instead.
     */
+   _mesa_bzero(&tmpNode, sizeof(tmpNode));
    alloc_temp_storage(emitInfo, &tmpNode, n->Store->Size);
 
    /* tmp = max(ch[0], ch[1]) */