[gdm] (11 commits) Non-fast-forward update to branch wip/nielsdg/meson

[Niels De Graef <nielsdg src gnome org>]

The branch 'wip/nielsdg/meson' 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:

  4dd05de... Allow building GDM with Meson.

Commits added to the branch:

  a2e255b... configure.ac: Remove execinfo.h check. (*)
  54cac35... Merge branch 'wip/nielsdg/remove-execinfo' into 'master' (*)
  9140e0c... configure.ac: remove libgen.h check. (*)
  a62084c... Merge branch 'wip/nielsdg/remove-other-headers' into 'maste (*)
  d6c2f28... configure.ac: Remove logindevperm.h check. (*)
  77be7bb... configure.ac: Remove Xft check. (*)
  d78232d... configure.ac: Remove XInput check. (*)
  20e658a... configure.ac: remove setpenv check. (*)
  2f9aaaf... configure.ac: Remove duplicate sys/sockio.h check. (*)
  724ce95... Merge branch 'wip/nielsdg/simplify-configure-ac' into 'mast (*)
  7844f4e... Allow building GDM with Meson.

(*) This commit already existed in another branch; no separate mail sent