Disable stack tagging in CloneStartRoutine.

We don't support running threads on a tagged stack. Untagging SP may
lead to accesses to the stack via a non-SP register, which will be tag
checked, and the check will fail. And indeed that's exactly what the
__bionic_clone function does in its first instruction. Fix the problem by
disabling HWASan and MTE stack tagging on CloneStartRoutine, and remove
the call to untag_address, as it is unnecessary.

Bug: 273807460
Change-Id: I94cc56c816897531c0113c856b54ec41b4aab874
diff --git a/tests/unistd_test.cpp b/tests/unistd_test.cpp
index 2a36460..4c21627 100644
--- a/tests/unistd_test.cpp
+++ b/tests/unistd_test.cpp
@@ -589,9 +589,10 @@
   TestGetTidCachingWithFork(CloneAndSetTid, exit);
 }
 
+__attribute__((no_sanitize("hwaddress", "memtag")))
 static int CloneStartRoutine(int (*start_routine)(void*)) {
   void* child_stack[1024];
-  return clone(start_routine, untag_address(&child_stack[1024]), SIGCHLD, nullptr);
+  return clone(start_routine, &child_stack[1024], SIGCHLD, nullptr);
 }
 
 static int GetPidCachingCloneStartRoutine(void*) {