OpenGL: Fix rendered textures being flipped.

This was because the clip space of OpenGL has an inverted Y compared to
other APIs. This commit:
 - Updates SPIRV-Cross to the latest version
 - Uses the new vertex.flip_vert_y option in ShaderModuleGL
 - Enables tests that are now passing in GL.

src/backend/opengl/ShaderModuleGL.cpp

@@ -57,6 +57,7 @@ namespace opengl {
 #else
         options.version = 440;
 #endif
+        options.vertex.flip_vert_y = true;
         compiler.set_options(options);
 
         // Rename the push constant block to be prefixed with the shader stage type so that uniform names