gcc: Link libssp_nonshared.a only on musl targets
glibc already provides the content for libssp_nonshared
in libc_nonshared.a therefore we dont need to make it
universal.
This also fixed build issues on glibc when linking statically
and using -fstack-protector
Fixed errors like
/mnt/a/oe/build/tmp/work/i586-bec-linux/aufs-util/3.14+gitAUTOINC+
bdfcc0dcfc-r0/recipe-sysroot/usr/lib/../lib/libc.a(stack_chk_fail.o): In function `__stack_chk_fail': /usr/src/debug/glibc/2.26-r0/git/debug/stack_chk_fail.c:27: multiple definition of `__stack_chk_fail_local' /mnt/a/oe/build/tmp/work/i586-bec-linux/aufs-util/3.14+gitAUTOINC+
bdfcc0dcfc-r0/recipe-sysroot/usr/lib/../lib/libssp_nonshared.a(libssp_nonshared_la-ssp-local.o):/usr/src/debug/gcc-runtime/7.1.0-r0/gcc-7.1.0/build.i586-bec-linux.i586-bec-linux/i586-bec-linux/libssp/../../../../../../../../work-shared/gcc-7.1.0-r0/gcc-7.1.0/libssp/ssp-local.c:47: first defined here collect2: error: ld returned 1 exit status
Signed-off-by: Khem Raj <raj.khem@gmail.com>
