(re_match_2): Fix string shortening (to fit `stop') to make sure

(re_match_2): Fix string shortening (to fit `stop') to make sure
POINTER_TO_OFFSET gives the same value before and after PREFETCH.
Use `dfail' to guarantee "atomic" matching.
(PTR_TO_OFFSET): Use POINTER_TO_OFFSET.
(debug): Now only active if > 0 rather than if != 0.
(DEBUG_*): Update for the new meaning of `debug'.
(print_partial_compiled_pattern): Add missing `succeed' case.
Use CHARSET_* macros in the charset(_not) branch.
Fix off-by-two bugs in `succeed_n', `jump_n' and `set_number_at'.
(store_op1, store_op2, insert_op1, insert_op2)
(at_begline_loc_p, at_endline_loc_p): Add prototype.
(group_in_compile_stack): Move to after its arg's types are declared
and add a prototype.
(PATFETCH): Define in terms of PATFETCH_RAW.
(GET_UNSIGNED_NUMBER): Add the usual `do { ... } while(0)' wrapper.
(QUIT): Redefine as a nop except for NTemacs.
(regex_compile): Handle intervals {,M} as if it was {0,M}.
Fix indentation of the greedy-op and shy-group code.
(at_(beg|end)line_loc_p): Fix argument's types.
(re_compile_fastmap): Ifdef out failure_stack_ptr to shut up gcc.
(re_search_2): Use POS_AS_IN_BUFFER.  Simplify `room' computation.
(MATCHING_IN_FIRST_STRING): Remove.
(re_match_2): Use POS_AS_IN_BUFFER.
Ifdef out failure_stack_ptr to shut up gcc.
Use FIRST_STRING_P and POINTER_TO_OFFSET.
Use QUIT unconditionally.