[GRASS-git] [OSGeo/grass] ce0811: CI: add -Wextra with a few exceptions (#2801)

[Nicklas Larsson]

  Branch: refs/heads/main
  Home:   https://github.com/OSGeo/grass
  Commit: ce08116b890253ee5fc79ba6fda1e43bd8ee3355
      https://github.com/OSGeo/grass/commit/ce08116b890253ee5fc79ba6fda1e43bd8ee3355
  Author: Nicklas Larsson <n_larsson at yahoo.com>
  Date:   2023-02-02 (Thu, 02 Feb 2023)

  Changed paths:
    M .github/workflows/gcc.yml
    M .github/workflows/macos_dependencies.txt
    M .github/workflows/macos_install.sh

  Log Message:
  -----------
  CI: add -Wextra with a few exceptions (#2801)

* Adding -Wextra compiler flag to the GCC and macOS CI runners, with
  -Wimplicit-fallthrough and -Wunused-parameter warnings temporarily exempted.

* Updates flex on macOS, as the default caused -Wsign-compare warnings.