Building rx's gas code atm fails:

Building rx's gas code atm fails:

rx-parse.c: In function ‘rx_parse’:
rx-parse.c:3774:9: error: passing argument 1 of ‘rx_error’ discards ‘const’
	qualifier from pointer target type [-Werror]
../../../gas/config/rx-defs.h:40:12: note:
	expected ‘char *’ but argument is of type ‘const char *’
cc1: all warnings being treated as errors

Signed-off-by: Mike Frysinger <vapier@gentoo.org>