[tsan] Deflake pthread_atfork_deadlock3

[vitalybuka]

Summary

sleep(1) does not guaranty afterfork order.
Also relative child/parent afterfork order is not important for this test so we
can just avoid checking that.

compiler-rt/test/tsan/pthread_atfork_deadlock3.c

-// RUN: %clang_tsan -O1 %s -o %t && %deflake %run %t | FileCheck %s
+// RUN: %clang_tsan -O1 %s -o %t && %deflake %run %t > %t.out
+// RUN: FileCheck %s --check-prefixes=CHECK,PARENT --input-file %t.out
+// RUN: FileCheck %s --check-prefixes=CHECK,CHILD --input-file %t.out
 // Regression test for
 // https://groups.google.com/g/thread-sanitizer/c/TQrr4-9PRYo/m/HFR4FMi6AQAJ
 #include "test.h"
 #include <errno.h>
 #include <signal.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/wait.h>
void afterfork() {
   barrier_wait(&barrier);
   barrier_wait(&barrier);
   write(2, "in afterfork\n", strlen("in afterfork\n"));
   static volatile long a;
   __atomic_fetch_add(&a, 1, __ATOMIC_RELEASE);
 }
 
 void afterfork_child() {
-  // Can't synchronize with barriers because we are
-  // in the new process, but want consistent output.
-  sleep(1);
   write(2, "in afterfork_child\n", strlen("in afterfork_child\n"));
   glob++;
 }
 
 void handler(int sig) {
   write(2, "in handler\n", strlen("in handler\n"));
   glob++;
 }

 
 // CHECK: in atfork
 // CHECK: in handler
 // CHECK: ThreadSanitizer: data race
 // CHECK:   Write of size 8
 // CHECK:     #0 handler
 // CHECK:   Previous write of size 8
 // CHECK:     #0 worker
-// CHECK: afterfork
-// CHECK: in handler
-// CHECK: afterfork_child
-// CHECK: CHILD
+// PARENT: afterfork
+// PARENT: in handler
+// CHILD: afterfork_child
+// CHILD: CHILD
 // CHECK: PARENT