macOS: bump to GCC 13 (for compilation and for use_dll)

The formulas are taken from commit 46401325ed2c4d72adb6f1592cf6096bb844b489 of
the homebrew-core repository.

The gcc.rb formula was modified by adding “cellar: :any” to all bottles (see
https://github.com/Homebrew/brew/blob/master/docs/Bottles.md).

The preprocessor has been updated accordingly.