Remove warnings

Remove warnings

	* src/regex.c (POP_FAILURE_POINT): Move DEBUG_STATEMENT to comply
	with C variable declaration rules. Cast the POP_FAILURE_POINTER return
	to proper const-ness.

	* src/regex.c (re_match_2_internal): Make re_char *'s d and dend
	const. Make scope p2 char* const. Make pdummy and sdummy const.
	Remove old comment.

Signed-off-by: Nelson Ferreira <nelson.ferreira@ieee.org>