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.
Adjust the depends of the GCC-8 cross compiler packages after the change
from pmbootstrap!1778. This does not have any effect (since the GCC-8
aports don't have !tracedeps in options, in contrary to the other GCC
aports we ship). But it makes sure that we don't get any changes after
running the repository maintenance script from here:
https://wiki.postmarketos.org/wiki/Repository_maintenance
[ci:skip-build]: cosmetic change, build would take too long anyway
