Remove unused regex code
This effectively reverts the parts of commit
01d9015868088fc3347511a095dce0195751c530 which add those sources
That commit also adds -fno-builtin-sscanf to CXXFLAGS. Probably that is part of
the same change, but I don't know for sure, so I've left that alone.
* Makefile.am (AM_CPPFLAGS): Remove regex from include path.
(@SETUP@_SOURCES): Remove regex.c.
* regex/config.h: Delete file.
* regex/re_comp.h: Delete file.
* regex/regcomp.c: Delete file.
* regex/regex.c: Delete file.
* regex/regex.h: Delete file.
* regex/regex_internal.c: Delete file.
* regex/regex_internal.h: Delete file.
* regex/regexec.c: Delete file.
Signed-off-by: Jon Turney <jon.turney@dronecode.org.uk>