build: Enable no-omit-frame-pointer for all non-plain builds

This is useful for local installations with e.g. the `release`
buildtype.
Further more, Fedora has been doing the same system wide and it
apparently was helpful in various ways, see also

Also add -mno-omit-leaf-frame-pointer, like Fedora.

https://blogs.gnome.org/chergert/2023/10/03/what-have-frame-pointers-given-us-anyway/

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3333>

clutter/meson.build

@@ -16,7 +16,6 @@ if buildtype != 'plain'
   if get_option('debug')
     clutter_debug_c_args += [
       '-DCLUTTER_ENABLE_DEBUG',
-      '-fno-omit-frame-pointer',
     ]
   else
     clutter_debug_c_args += [