[poppler] Poor error handling in gmem.c

[Florian Weimer]

With the recent merge from xpdf 3.01, problematic error handling code
has been introduced in to poppler:

void *gmallocn(int nObjs, int objSize) {
  int n;

  n = nObjs * objSize;
  if (objSize == 0 || n / objSize != nObjs) {
    fprintf(stderr, "Bogus memory allocation size\n");
    exit(1);
  }
  return gmalloc(n);
}

Invalid input data (not just an out-of-memory condition) results in
the whole process being terminated, which is not a good thing to do
for a library.

The gmallocn function is also incorrect because according to the C
standard, the if condition can be assumed to be always false, but this
is best discussed with the xpdf folks.