Merge branch 'pks-meson-fixes' of github.com:pks-gitlab/git-gui

* 'pks-meson-fixes' of github.com:pks-gitlab/git-gui:
  git-gui: wire up "git-gui--askyesno" with Meson
  git-gui: massage "git-gui--askyesno" with "generate-script.sh"
  git-gui: prefer shell at "/bin/sh" with Meson
  git-gui: fix use of GIT_CEILING_DIRECTORIES

Signed-off-by: Johannes Sixt <j6t@kdbg.org>