- Re-enable readability-magic-numbers in .clang-tidy (strict) for
production code.
- Add .clang-tidy-test (relaxed) that excludes magic-numbers for
*_test.cc, *_benchmark.cc, and *_fuzz.cc files.
- clang_tidy.py now selects config by file suffix via _config_for_file(),
matching _test./_benchmark./_fuzz. against the filename.
- Exclude readability-magic-numbers from .clang-tidy checks; test and
benchmark files contain literal test data that should not be treated as
magic numbers.
- Add detect_system_include_extra_args() to clang_tidy.py that queries
gcc -print-file-name=include at runtime, passing the result via
--extra-arg=-isystem to the static clang-tidy binary. This fixes the
'stddef.h not found' error on systems where the bundled static binary
lacks a resource directory, without hardcoding any paths.