[gtest] Increase stack size for child process in EXPECT_DEATH implementation

[waltl]

Summary

Currently it is getpagesize() which is often only 4k, which is
insufficient for some ASan tests with 32-byte shadow granularity.
Make it at least 8k.

llvm/utils/unittest/googletest/src/gtest-death-test.cc

GTEST_DEATH_TEST_CHECK_SYSCALL_(sigaction(
       SIGPROF, &ignore_sigprof_action, &saved_sigprof_action));
 #   endif  // GTEST_OS_LINUX
 
 #   if GTEST_HAS_CLONE
   const bool use_fork = GTEST_FLAG(death_test_use_fork);
 
   if (!use_fork) {
     static const bool stack_grows_down = StackGrowsDown();
-    const size_t stack_size = getpagesize();
+    const size_t stack_size = std::max(getpagesize(), 8192);
     // MMAP_ANONYMOUS is not defined on Mac, so we use MAP_ANON instead.
     void* const stack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE,
                              MAP_ANON | MAP_PRIVATE, -1, 0);
     GTEST_DEATH_TEST_CHECK_(stack != MAP_FAILED);
 
     // Maximum stack alignment in bytes:  For a downward-growing stack, this
     // amount is subtracted from size of the stack space to get an address
     // that is within the stack space and is aligned on all systems we care