fix building with selinux enabled

Libs go into LIBS and after objects, not LDFLAGS.

We don't want to pass -DHAVE_SELINUX via the command line as the generated
config.h already defines it for us.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
ignore gdb related files

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
get selinux build info via pkg-config

They've started linking libselinux against more things (like libpcre),
so use pkg-config to get its dependency info.

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