This commit minimizes libgcc's gccConfigureFlags, and -- importantly
-- includes the three flags needed in order to prevent
`inhibit_libc` from becoming active.
This commit restores the pkgs/development/libraries/gcc/libgcc
package, which was deleted by commit 9818d120be.
We need to be able to build libgcc separately from gcc in order to
avoid a circular dependency. Nixpkgs is unusual -- unlike any other
distribution, it cannot tolerate circular dependencies between
dynamically linked libraries. Because of this, upstream is
extremely unsympathetic to the trouble that the glibc<->gcc circular
dependency causes for us; if we don't solve it ourselves it will not
be solved.
`libgcc` is not usable as is and as a result no packages use it today.
`gcc.cc.libgcc` should provide the same library. But ideally it should
not be used at all as it's an implementation detail of `gcc` support
libraries.
Done with the help of https://github.com/Mindavi/nixpkgs-mark-broken
Tool is still WIP but this is one of the first results.
I manually audited the results and removed some results that were not valid.
Note that some of these packages maybe should have more constrained platforms set
instead of broken set, but I think not being perfectly correct is better than
just keep trying to build all these things and never succeeding.
Some observations:
- Some darwin builds require XCode tools
- aarch64-linux builds sometimes suffer from using gcc9
- gcc9 is getting older and misses some new libraries/features
- Sometimes tools try to do system detection or expect some explicit settings for
platforms that are not x86_64-linux
