With MALLOC_CHECK_ env var set to valid values (1,2, or 3),
the realloc implementation doesn't set ENOMEM when it should.

Running the following shows that errno is incorrectly set to 0:


#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
int main ()
{
  void *p;
  void* p2 = malloc ((unsigned long) 1);
  errno = 0;
  p = realloc (p2, (unsigned long) PTRDIFF_MAX + 1);
  fprintf (stderr, "p=%p errno=%d\n", p, errno);
  return 0;
}


gcc realloc.c
MALLOC_CHECK_=1 ./a.out