[glib] (5 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:

  b4560e8... param: Add a value_is_valid vfunc
  251c664... param: Add g_param_value_is_valid
  8ecf667... Add tests for g_param_value_is_valid
  e8fe9d0... gobject: Use value_is_valid

Commits added to the branch:

  53516e2... param: Add a value_is_valid vfunc
  1e544b9... param: Add g_param_value_is_valid
  68534ec... Add tests for g_param_value_is_valid
  bb3052b... Add another test for g_param_value_is_valid
  b64bb9d... gobject: Use value_is_valid