gcc: enable build-id in gcc-cross-initial

gcc: enable build-id in gcc-cross-initial

Normal gcc-cross has build-id feature enabled by default, so most of
target binaries has build-id. But libc (glibc, musl) doesn't have
build-id, because it is built with gcc-cross-initial.

Build-id is a useful feature, so enable it for gcc-cross-initial too.

Signed-off-by: Taras Kondratiuk <takondra@cisco.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>