* lib/regex_internal.c (re_string_reconstruct): Handle

* lib/regex_internal.c (re_string_reconstruct): Handle
offset < pstr->valid_raw_len && pstr->offsets_needed case.
Ensure no bytes read before raw_mbs array.  Pass a saved copy of
pstr->valid_len - 1 rather than pstr->valid_raw_len - 1 to
re_string_context_at.
* m4/regex.m4 (gl_REGEX): Check for locale.h, since the test
now requires it.
(gl_PREREQ_REGEX): Don't check for locale.h any more, since
gl_REGEX now does it for us.
(gl_REGEX): Add test taken from
http://sourceware.org/ml/libc-hacker/2006-09/msg00008.html.