[gimp] build: clean out obsolete Windows-specific patches.

[Jehan <jehanp src gnome org>]

commit 18785bf9f1addf1f3911ec55401e4955e9d64383
Author: Jehan <jehan girinstud io>
Date:   Thu May 20 19:58:08 2021 +0200

    build: clean out obsolete Windows-specific patches.
    
    - libwmf patch for issue #4061 is applied upstream (libwmf). Even though
      no new libwmf release happened, the MSYS2 package applied the patch to
      libwmf 0.2.12. So it's in our installer. Thanks to lillolollo for
      staying on top of things, as usual.
      Cf. https://github.com/msys2/MINGW-packages/pull/6977
    - glib permission issue (#4594 about GIMP preventing the third-party
      software Spotify from starting) is included since glib 2.67.6/2.68.0.
      Since MSYS2 uses glib 2.68.2, it's all good.
    - patch for deprecated GTK+2.24 was kept in `master` repo mostly as a
      reminder of having to deal with issue #1082 (former bug 780979) about
      transparent windows from other software interfering with GIMP. This
      was fixed as gtk!2767 which is available since GTK 3.24.27. MSYS2 uses
      GTK 3.24.29 to this day.
      Note that this patch is still relevant in the GIMP 2.10 series (hence
      in gimp-2-10 branch), not in the current GIMP 2.99 series.

 ...-right-permissions-for-directory-watching.patch | 31 ---------------------
 build/windows/patches/gtk+-2.24-bug780979.patch    | 32 ----------------------
 ...-libwmf-check-incoming-metric-for-nullptr.patch | 26 ------------------
 3 files changed, 89 deletions(-)