This update for gn fixes the following issues:

- Update to version 0.20260331:
  * Add modulemap generation to GN.
  * Support building gn without a .git directory.
  * Limit the maximum number of GN worker threads to 32.
  * Remove premature target writing before validation during `gn gen`.
  * Only run target checks in background threads during resolution.
  * Add additional files to gitignore
  * Add `inputs` parameter to `tool`.
  * Unit test foo* not just *foo patterns
  * Unit test edge cases around consecutive \b in patterns
  * Reject newlines in string config values (defines, cflags, etc.)
  * Set clang-format to use C++20
  * Run formatter
  * Bump min mac version flag.
  * Add --error-limit flag to control error output count
  * [gn] Fix Value::operator== for empty lists
  * [gn] Optimize Value::LIST with Copy-On-Write using nullptr
  * Capture C++ modules compilation commands in compile_commands.json
  * Output -fmodule-map-file as well as -fmodule-file for module dependencies.
  * Optimize HeaderChecker by parallelizing ReachabilityCache pre-calculation and removing lock contention.
  * Optimize HeaderChecker file I/O by parsing files only once
  * Optimize reachability cache to drastically reduce BFS executions
  * Remove unused targets_count_ in HeaderChecker
  * Apply clang-format
  * Use high-performance cores on Apple Silicon for worker pool
  * Optimize HeaderChecker::IsDependencyOf using HashTableBase
  * [perf] Optimize HeaderChecker BFS using reserve()
  * [perf] Share ResolvedTargetData across worker threads
  * [perf] Cache dependency checks in HeaderChecker
  * [test] Fix SetupTest.AbsolutePythonPathInsideRootDir on macOS
  * [mac] Update minimum macOS version to 10.12
  * Include validations when collecting metadata
  * Fix target being written twice under certain circumstances
  * Add validation support to gn analyze/desc/path/refs
  * Fix race condition when using validations
  * Add pcm files to the deps of phony target
  * Add `validations` dependency type to targets
  * Fix result of Scheduler::Run() with empty work queue
  * Add conductor setup files
  * Improve writing runtime deps
  * Unit test label user visible name
  * Improve error message for rebase_path builtin
  * Minor table-driven test refactor
  * win: Use relative path for python in ninja files if possible