[clang-tools-extra] [clang-tidy][readability] Ignore macros in function-size check (PR #199549)

[via cfe-commits]

savchart wrote:

Added a test for this case with one extra non-macro statement.

With only `BODY`, the function is skipped: after ignoring the macro-expanded statement, `FI.Statements == 0`, and `FunctionSizeCheck::check()` returns early.

This still tests the intended behavior: `IgnoreMacros` does not affect `ParameterThreshold`, since parameter counting is done in `check()`, not during AST traversal.

https://github.com/llvm/llvm-project/pull/199549