Add coverage instrumentation flags to compile commands

Summary:
Add coverage instrumentation flags to the compilation of C   source files
to instrument them.

The only difference between executables and libraries is that libraries consider non-exported dependencies to determine if they need to be instrumented or not, but they only propagate the information of exported deps.

Reviewed By: Nekitosss

Differential Revision: D58779016

fbshipit-source-id: ed0e30a297dcce8518383888fa67b0c91dcabb21

Move mod buildfiles out of mod legacy_configs

Summary: `buildfiles` is a user of buckconfigs, not part of the implementation.

Reviewed By: cjhopman

Differential Revision: D58610698

fbshipit-source-id: f8252eff384903d09aeba0389eca5d529d5c39f3

rust-project: Warn on unowned files

Summary: Log a warning message if we can't determine the owner of a file passed to `develop`, but _is_ in fbsource (i.e., we already log if buck can't determine an owner because it's outside of the repo, but now we also log if it's in the repo but unowned).

Reviewed By: Wilfred

Differential Revision: D57947948

fbshipit-source-id: 1fd06b41341503b58e39748e994cd14f18880a6c

Update the build modes to use for debug/release in Xcode

Reviewed By: blackm00n

Differential Revision: D57332237

fbshipit-source-id: 7293ff5e896130eb0cfbf6abfcad810d2d20879a

Prefer pub(crate) for visibility

Summary:
`pub(crate)` generally gives better 'unused definition' warnings from rustc, because it knows the definition isn't used elsewhere.

Use `pub(crate)` wherever we can, and fix definitions that didn't need to be `pub` or `pub(crate)`.

Reviewed By: samkevich

Differential Revision: D56778389

fbshipit-source-id: b73364f96e9601e94a1196b25f78e92968a3edb0

Simplify select tests

Summary: Pass resolved select keys to `select_the_most_specific` instead of passing `ResolvedConfigurationSettings` which contains incompatible keys too.

Reviewed By: JakobDegen

Differential Revision: D56121980

fbshipit-source-id: 1d278c1a746a6fac92303f20a2cbc05a37730a79

cells: Repro broken cell handling in file watcher

Summary: Explanation in the diff. This seems pretty bad, I'm not going to fix it though, because it's kind of hard.

Reviewed By: stepancheg

Differential Revision: D55573384

fbshipit-source-id: b7b4483fcf34179bdeb18e33713ab7ce9422e857

buck2: glossary: snake casing nit

Summary: ^

Reviewed By: JakobDegen

Differential Revision: D54929757

fbshipit-source-id: 12bc297b977c82062bdce9d5c41c6ff5b6b6a870

Pass correct rpath origin setting to linker on Darwin for Haskell (fa…

…cebook#567)

Summary:
This is a follow-up to facebook#536 which fixes a problem on Darwin when trying to execute a haskell_binary fails with:

```
dyld[13654]: Library not loaded: rpath/lib_backend.dylib
  Referenced from: <no uuid> /Users/runner/work/buck-out/v2/gen/root/6e975d09ae66fe71/backend/one-off-task/__one-off-task__/one-off-task
  Reason: tried: '$ORIGIN/__one-off-task__shared_libs_symlink_tree/lib_backend.dylib' (no such file), '$ORIGIN/__one-off-task__shared_libs_symlink_tree/lib_backend.dylib' (no such file), '/usr/local/lib/lib_backend.dylib' (no such file), '/usr/lib/lib_backend.dylib' (no such file, not in dyld cache)
```

Pull Request resolved: facebook#567

Reviewed By: simonmar

Differential Revision: D54346421

Pulled By: JakobDegen

fbshipit-source-id: 00d5d9fd44fb52b24f80bfecdf0cf3683b1e44b1

Support GODEBUG env-var

Summary: Support setting [GODEBUG](https://go.dev/doc/godebug) on toolchain level

Reviewed By: leoleovich

Differential Revision: D53769175

fbshipit-source-id: 5a685f74ff9ad44a22f7fe2271a232697836132f