glsl_shader_gen: Remove invariant qualifier (#7376)

* glsl_shader_gen: Remove invariant qualifier

* Causes visual regressions in Pokemon with RADV

* rasterizer_cache: Clear null surface to transparent

src/video_core/shader/generator/glsl_shader_gen.cpp

@@ -76,7 +76,13 @@ static std::string GetVertexInterfaceDeclaration(bool is_output, bool use_clip_p
     if (is_output && separable_shader) {
         // gl_PerVertex redeclaration is required for separate shader object
         out += "out gl_PerVertex {\n";
+        // Apple Silicon GPU drivers optimize more aggressively, which can create
+        // too much variance and cause visual artifacting in games like Pokemon.
+#ifdef __APPLE__
         out += "    invariant vec4 gl_Position;\n";
+#else
+        out += "    vec4 gl_Position;\n";
+#endif
         if (use_clip_planes) {
             out += "    float gl_ClipDistance[2];\n";
         }