configure: libtool < 2.4.6 doesn't work with fstack-protector-strong

* configure.ac: GCC -fstack-protector-strong gives undefined symbol error
  when linking on __stack_chk_fail_local with libtool < 2.4.6.  The gcc arg
  is not passed on when linking.  OpenIndiana hipster has 2.4.2 at the
  moment. Test the libtool version and drop the arg and warn the user.
1 file changed