(SKIP_SOMETHING, find_occurs_in_text):

(SKIP_SOMETHING, find_occurs_in_text):
Store match length in regoff_t,
not int.  Assume that negative return values less than -2
represent regoff_t overflow.
(matcher_error): New function.
(SKIP_SOMETHING, find_occurs_in_text): Use it to report matcher errors.
(alloc_and_compile_regex): No longer any need to worry about
int versus size_t mismatch.