testsuite: Make GLES testsuite run use GLES 2

We want to support GLES 2, so make sure we test that support.

Also force-disable common extensions we don't explicitly check for and
don't want to accidentally use.

testsuite/meson.build

@@ -17,7 +17,10 @@ setups = [
   { 'backend': 'wayland', 'if': wayland_enabled, 'is_default': true, },
   { 'name': 'wayland_gles',
     'backend': 'wayland', 'if': wayland_enabled,
-    'env': ['GDK_DEBUG=gl-gles,default-settings'], },
+    'env': ['GDK_DEBUG=gl-gles,default-settings',
+            'MESA_GLES_VERSION_OVERRIDE=2.0',
+            'MESA_EXTENSION_OVERRIDE=-GL_OES_vertex_array_object',
+           ], },
   { 'backend': 'win32', 'if': os_win32 },
   { 'backend': 'broadway', 'if': broadway_enabled, },
   { 'name': 'wayland_smalltexture',