[hwasan] Fix TestCases/thread-uaf.c.

[eugenis]

Summary

On newer glibc, this test detects an extra match somewhere under
pthread_getattr_np. This results in Thread: lines getting spread out in
the report and failing to match the CHECKs.

Fix the CHECKs to allow this possibility.

[fmayer]

lgtm

compiler-rt/test/hwasan/TestCases/thread-uaf.c

 // Tests UAF detection where Allocate/Deallocate/Use
 // happen in separate threads.
-// RUN: %clang_hwasan %s -o %t && not %run %t 2>&1 | FileCheck %s
+// RUN: %clang_hwasan %s -o %t && not %run %t > %t.out 2>&1
+// RUN: cat %t.out | FileCheck %s
+// RUN: cat %t.out | FileCheck --check-prefix=CHECK-THREAD %s
 // REQUIRES: stable-runtime
 
 #include <pthread.h>
 #include <stdlib.h>
 #include <stdio.h>
 
 #include <sanitizer/hwasan_interface.h>
 
void *Use(void *arg) {
   // CHECK: ERROR: HWAddressSanitizer: tag-mismatch on address
   // CHECK: WRITE of size 1 {{.*}} in thread T3
   // CHECK: thread-uaf.c:[[@LINE-3]]
   // CHECK: Cause: use-after-free
   // CHECK: freed by thread T2 here
   // CHECK: in Deallocate
   // CHECK: previously allocated here:
   // CHECK: in Allocate
-  // CHECK-DAG: Thread: T2 0x
-  // CHECK-DAG: Thread: T3 0x
-  // CHECK-DAG: Thread: T0 0x
-  // CHECK-DAG: Thread: T1 0x
+  // CHECK-THREAD-DAG: Thread: T2 0x
+  // CHECK-THREAD-DAG: Thread: T3 0x
+  // CHECK-THREAD-DAG: Thread: T0 0x
+  // CHECK-THREAD-DAG: Thread: T1 0x
   __sync_fetch_and_add(&state, 1);
   return NULL;
 }
 
 int main() {
   __hwasan_enable_allocator_tagging();
   pthread_t t1, t2, t3;