(PUSH_FAILURE_INT, POP_FAILURE_INT): Use WIDE_INT.

(PUSH_FAILURE_INT, POP_FAILURE_INT): Use WIDE_INT.
(WIDE_INT): Defined (two alternate definitions).

(C_ALLOCA): Undef it, if __GNUC__.

(REGEX_ALLOCATE_STACK, REGEX_REALLOCATE_STACK)
(REGEX_FREE_STACK): New macros.
(INIT_FAIL_STACK, DOUBLE_FAIL_STACK, FREE_VARIABLES): Use them.
(re_max_failures) [REL_ALLOC]: Alternative larger initial value.
(re_compile_fastmap): Use REGEX_FREE_STACK.
(re_match_2_internal): Always call FREE_VARIABLES before returning.
Always init regstart, old_regstart, etc. whenever MATCH_MAY_ALLOCATE
is defined.
(FREE_VARIABLES) [REL_ALLOC]: Define non-trivially.