Revert "Reintroduce -fstack-protector"

http://lists.freedesktop.org/archives/input-tools/2013-September/000332.html
See above a detailed reasoning, but Colin Walters put it this way:

"At a high level, I think components (git repositories) should feel free
to set up default warning flags and possibly use a targeted subset of
-Werror=foo.  But please don't inject non-warning flags like this unless
there is a very good reason.

The right way to do -fstack-protector is to have something like
redhat-rpm-config or other global CFLAGS system controlling *all*
components."

Thus, reverting the -fstack-protector flag. This doesn't completely address
Colin's comments, we still use a few other flags. But this one is the one
that causes real headaches, so drop it.

This reverts commit f5e65ea3ce.

configure.ac

@@ -67,7 +67,6 @@ if test "x$GCC" = "xyes"; then
 				-fdata-sections \
 				-fno-strict-aliasing \
 				-fdiagnostics-show-option \
-				-fstack-protector \
 				-fno-common])
 fi
 AC_SUBST([GCC_CFLAGS], $with_cflags)