useless-if-before-free: avoid false-positive

useless-if-before-free: avoid false-positive

* build-aux/useless-if-before-free: Adjust regexp for the non-brace
disjunct so that it too requires a terminating ";".  Without that,
this script would identify as useless one statement from gcc that
was not:
  if (aligned_ptr)
    free (((void **) aligned_ptr) [-1]);