Log Message:
lang/gcc*: skip some RELRO checks when --disable-boostrap

This relates to the case when GCC is built using clang host CC. In that
case the runtime libraries are not built with RELRO for some reason.

for the gcc*-libs/ packages, mark them as RELRO_SUPPORTED=no unconditionally.
RELRO status depends on how the parent gcc package was built so we don't
need nor care about the RELRO status here.