[Ada] Add gcc specs with vxworks7 base addresses for cert
gcc/ada/
* vxworks7-cert-rtp-link.spec: Replace the definition of
__wrs_rtp_base with the base_link spec.
* vxworks7-cert-rtp-base-link.spec: Add base_link spec with
__wrs_rtp_base definition for all architectures.
* vxworks7-cert-rtp-base-link__ppc64.spec: Add base_link spec
with __wrs_rtp_base definition for ppc64.
* vxworks7-cert-rtp-base-link__x86.spec: Add base_link spec with
__wrs_rtp_base definition for x86.
* vxworks7-cert-rtp-base-link__x86_64.spec: Add base_link spec
with __wrs_rtp_base definition for x86_64.