Lots of packages are missing versions in their name. This adds them
where appropriate. These were found with this command:
$ nix-env -qa -f. | grep -v '\-[0-9A-Za-z.-_+]*$' | grep -v '^hook$'
See issue #41007.
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Using the configure option relieves us of the patch and passing the path
via the env var in many places. Also the env var may not be inherited
when components like gdm spawn new sessions.
The most complex problems were from dealing with switches reverted in
the meantime (gcc5, gmp6, ncurses6).
It's likely that darwin is (still) broken nontrivially.