[glib] (8 commits) ...Merge branch 'master' into 'master'

[Philip Withnall <pwithnall src gnome org>]

Summary of changes:

  e0f2671... gio: icons should fallback to non-preferred style appropria
  9290044... gio: generate (non-)symbolic and fallback variants for ever
  5fb6d78... gio: do not add an icon name already in the list.
  8f729c0... gio: update icon list when appending or prepending an icon 
  2cac838... gio: fix g-icon tests to follow recent changes.
  ab53a54... gio: fixing duplicate icons and review comments.
  00cc158... gio: adding a g-icon test.
  f876f41... Merge branch 'master' into 'master'