Make the version match Alpine's gcc again. Fixes libstdc++ unsatisfiable
constrains related error messages (because the libstdc++ generated by
these cross-* packages has the same pkgver and pkgrel again as the one
provided by Alpine's gcc package).
[ci:skip-build]: won't finish in time
The upstream compat test case will still fail after this, there are more
issues that need to be resolved. I'm on it.
