[glib] (3 commits) Non-fast-forward update to branch param-speedups2

[Matthias Clasen <matthiasc src gnome org>]

The branch 'param-speedups2' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  d4f3add... param: Add g_param_value_is_valid
  98739e9... Add tests for g_param_value_is_valid
  d76e5bf... gobject: Use value_is_valid
  a065a1d... Add g_param_value_is_valid to the docs

Commits added to the branch:

  935e981... param: Add g_param_value_is_valid
  fe81083... Add tests for g_param_value_is_valid
  791febc... gobject: Use value_is_valid