configure: accept __stack_chk_fail_local for ssp support too [BZ #20662]

When glibc is compiled with gcc 6.2 that has been configured with
--enable-default-pie and --enable-default-ssp, the configure script
fails to detect that the compiler has ssp turned on by default when
being built for i686-linux-gnu.

This is because gcc is emitting __stack_chk_fail_local but the
script is only looking for __stack_chk_fail.  Support both.

Example output:
checking whether x86_64-pc-linux-gnu-gcc -m32 -Wl,-O1 -Wl,--as-needed
implicitly enables -fstack-protector... no

(cherry picked from commit c7409ade)