[test][msan] Update for noundef on retval

GitOrigin-RevId: e92fe7af3f9d7a660e026912852c8ce401331c03
diff --git a/test/msan/stack-origin2.cpp b/test/msan/stack-origin2.cpp
index f47a393..1c9d66a 100644
--- a/test/msan/stack-origin2.cpp
+++ b/test/msan/stack-origin2.cpp
@@ -20,17 +20,19 @@
 
 #include <stdlib.h>
 
-extern "C"
-int f(int depth) {
-  if (depth) return f(depth - 1);
+int t;
 
-  int x;
-  int *volatile p = &x;
-  return *p;
+extern "C" void f(int depth) {
+  if (depth)
+    return f(depth - 1);
+
+  volatile int x;
+  t = x;
 }
 
 int main(int argc, char **argv) {
-  return f(1);
+  f(1);
+  return t;
   // CHECK: WARNING: MemorySanitizer: use-of-uninitialized-value
   // CHECK: {{#0 0x.* in main .*stack-origin2.cpp:}}[[@LINE-2]]