This PR also sets `alwayslink=True` for `//libc/test:LibcUnitTest`. This ensures that the `main` function provided always gets linked into a test target. While not strictly necessary, it makes it so tests like45d8759cbe/libc/test/include/signbit_test.cwill give a duplicate symbol error if they incorrectly depend on `//libc/test:LibcUnitTest`. This PR is missing tests for generated header includes since the current Bazel setup lacks generated headers or a mechanism to run hermetic tests. CMake version of the header include tests:a2ce564720/libc/test/include/CMakeLists.txt (L515)See issue https://github.com/llvm/llvm-project/issues/134780