* Sema: implement linksection on functions
* Implement function linksection in Sema.
* Don't clobber function linksection/align/addrspace in Sema.
* Fix copy-paste typo in tests.
* Add a bunch of missing test_step.dependOn.
* Fix checkInSymtab match.
Closes#12546
MachO linker now handles `-needed-l<name>`, `-needed_library=<name>`
and `-needed_framework=<name>`. While on macOS `-l` is equivalent
to `-needed-l`, and `-framework` to `-needed_framework`, it can be
used to the same effect as on Linux if combined with `-dead_strip_dylibs`.
This commit also adds handling for `-needed_library` which is macOS
specific flag only (in addition to `-needed-l`).
Finally, in order to leverage new linker testing harness, this commit
added ability to specify lowering to those flags via `build.zig`:
`linkSystemLibraryNeeded` (and related), and `linkFrameworkNeeded`.
