[ASAN][DARWIN] Remove getpwnam(NULL) test for undefined behavior

Reverting a patch that was added to test for getpwnam(NULL) -- it was noted at the time the behavior might have been a bug, however the patch was added for binary compatibility. Because of the change in the expected behavior, we are reverting this commit, as the test added is no longer passing.

Update: Rather than reverting the original commit, updating this to only remove the unnecessary test.

Original Patch: https://reviews.llvm.org/D40052

rdar://98592334

compiler-rt/test/asan/TestCases/Darwin/getpwnam.c

@@ -1,15 +0,0 @@
-// RUN: %clang_asan %s -o %t
-// RUN: %run %t 2>&1 | FileCheck %s
-
-#include <pwd.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/types.h>
-
-int main(int argc, const char * argv[]) {
-  getpwnam(NULL);
-  fprintf(stderr, "Finished.\n");
-  return 0;
-}
-
-// CHECK: Finished.