build: Don't link system libraries when building a static library

[jayschwa]

Previously, system libraries like libX11.so were passed to ar rcs. Consumers of the archive receive warnings about invalid contents.

Fixes #20476

[jayschwa]

An alternate solution might remove the non-object comp.link_inputs earlier in the call stack, but I am unfamiliar with this code and don't know which is better.

[jayschwa]

I'm not positive, but the CI failure seems unrelated to my change:

test
+- test-c-abi
   +- run test-c-abi-x86_64-linux.4.19...6.11.5-musl.2.28-x86_64-Debug-selfhosted-no-lld
      +- zig test test-c-abi-x86_64-linux.4.19...6.11.5-musl.2.28-x86_64-Debug-selfhosted-no-lld Debug x86_64-linux-musl 1 errors
:1:1: error: clang frontend command failed with exit code 139 (use -v to see invocation)
:1:1: note: diagnostic msg: 
            ********************
            
            PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
            Preprocessed source(s) and associated run script(s) are located at:
:1:1: note: diagnostic msg: /tmp/cfuncs-2640e2.c
:1:1: note: diagnostic msg: /tmp/cfuncs-2640e2.sh
:1:1: note: diagnostic msg: 
            
            ********************
error: warning(compilation): failed to delete '/home/ci/actions-runner2/_work/zig/zig/zig-local-cache/tmp/9fc7f0b5d2a4f502-cfuncs.o.d': FileNotFound

[andrewrk]

Ummm shouldn't this happen much earlier?

If shared libraries are specified on the CLI when outputting a static archive, then the user should receive an error.

If those shared libraries are coming from the frontend, then the frontend should refrain from adding that work into the pipeline in the first place.

[jayschwa]

I reworked this so the build system does not pass -lfoo to zig build-lib ... -static. It does not produce an error if someone were to manually zig build-lib ... -lfoo ... -static from the command line. I can try that too, but I need more time to acquaint myself with that code. As-is, this seems to resolve the issue I was seeing in the wild with development builds of Zig.