remove OSMesa (#9708)

* remove OSMesa

OSMesa is depricated for quite a while and got removed with Mesa 25.1.0

* remove OSMesa from all buildfiles, readmes, etc…

---------

Co-authored-by: Noisyfox <timemanager.rick@gmail.com>

flatpak/io.github.softfever.OrcaSlicer.yml

@@ -36,29 +36,6 @@ modules:
         url: https://gstreamer.freedesktop.org/src/gst-plugins-good/gst-plugins-good-1.22.8.tar.xz
         sha256: e305b9f07f52743ca481da0a4e0c76c35efd60adaf1b0694eb3bb021e2137e39
 
-  # For libOSMesa
-  - name: mesa
-    buildsystem: meson
-    config-opts:
-      - -Dosmesa=classic
-      - -Ddri-drivers=[]
-      - -Dgallium-drivers=[]
-      - -Dvulkan-drivers=[]
-      - -Dplatforms=[]
-    build-options:
-      arch:
-        aarch64:
-          config-opts:
-            - -Dlibunwind=disabled
-    cleanup:
-      - /share/drirc.d
-      - /include
-      - "*.a"
-    sources:
-      - type: archive
-        url: https://archive.mesa3d.org/older-versions/20.x/mesa-20.2.6.tar.xz
-        sha256: f12ca3c6c622f11cd79ad66b4220f04514fa96f795062fe92a37339ab19885db
-
   - name: glu
     config-opts:
       - --disable-static