[feat] clang-tidy: add optional gcc-install-dir arg

Without the argument, clang (clang-tidy) discovers a gcc installation
automatically on the system, for example,
```
% clang -v
Ubuntu clang version 18.1.8 (++20240731024944+3b5b5c1ec4a3-1~exp1~20240731145000.144)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/13
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/13
```

However, users may want to switch off the discovery and specify a
version, exactly.

```
% clang -v --gcc-install-dir=/usr/lib/gcc/x86_64-linux-gnu/12
Ubuntu clang version 18.1.8 (++20240731024944+3b5b5c1ec4a3-1~exp1~20240731145000.144)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/12
```

This is especially relevant for, but not limited to, hermetic
toolchains.

See also

  This patch ports erenon/bazel_clang_tidy#88
  to rules_lint.

Author: Synss

lint/clang_tidy.bzl

@@ -37,6 +37,7 @@ clang_tidy = lint_clang_tidy_aspect(
 ```
 """
 
+load("@bazel_skylib//rules/directory:providers.bzl", "DirectoryInfo")
 load("@bazel_tools//tools/build_defs/cc:action_names.bzl", "ACTION_NAMES")
 load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
 load("//lint/private:lint_aspect.bzl", "LintOptionsInfo", "OPTIONAL_SARIF_PARSER_TOOLCHAIN", "OUTFILE_FORMAT", "noop_lint_action", "output_files", "parse_to_sarif_action", "patch_and_output_files")
@@ -262,6 +263,14 @@ def _get_args(ctx, compilation_context, srcs):
 def _get_compiler_args(ctx, compilation_context, srcs):
     # add args specified by the toolchain, on the command line and rule copts
     args = []
+
+    if ctx.attr._gcc_install_dir:
+        gcc_install_dir = ctx.attr._gcc_install_dir[0].files.to_list()
+        if len(gcc_install_dir) > 1:
+            fail("gcc_install_dir must contain at most one directory")
+        for dir in gcc_install_dir:
+            args.append("--gcc-install-dir=" + dir.path)
+
     rule_flags = ctx.rule.attr.copts if hasattr(ctx.rule.attr, "copts") else []
     sources_are_cxx = _is_cxx(srcs[0])
     if (sources_are_cxx):
@@ -409,7 +418,15 @@ def _clang_tidy_aspect_impl(target, ctx):
     parse_to_sarif_action(ctx, _MNEMONIC, raw_machine_report, outputs.machine.out)
     return [info]
 
-def lint_clang_tidy_aspect(binary, configs = [], global_config = [], header_filter = "", lint_target_headers = False, angle_includes_are_system = True, verbose = False):
+def lint_clang_tidy_aspect(
+        binary,
+        configs = [],
+        global_config = [],
+        gcc_install_dir = [],
+        header_filter = "",
+        lint_target_headers = False,
+        angle_includes_are_system = True,
+        verbose = False):
     """A factory function to create a linter aspect.
 
     Args:
@@ -427,6 +444,8 @@ def lint_clang_tidy_aspect(binary, configs = [], global_config = [], header_filt
             files which may be used for formatting fixes.
         global_config: label of a single global .clang-tidy file to pass to clang-tidy on the command line. This
             will cause clang-tidy to ignore any other config files in the source directories.
+        gcc_install_dir: optional, label of a `Directory` from the skylib library pointing to the gcc install
+            directory.  The argument is passed to the underlying clang as `--gcc-install-dir`.
         header_filter: optional, set to a posix regex to supply to clang-tidy with the -header-filter option
         lint_target_headers: optional, set to True to pass a pattern that includes all headers with the target's
             directory prefix. This crude control may include headers from the linted target in the results. If
@@ -455,6 +474,10 @@ def lint_clang_tidy_aspect(binary, configs = [], global_config = [], header_filt
                 default = global_config,
                 allow_files = True,
             ),
+            "_gcc_install_dir": attr.label_list(
+                default = gcc_install_dir,
+                providers = [DirectoryInfo],
+            ),
             "_lint_target_headers": attr.bool(
                 default = lint_target_headers,
             ),