EEVEE: Fix missing function implementation for volumetric materials

This was leading to linking errors.

Fixes T97779 Regression: World volume noise stopped working

source/blender/draw/engines/eevee/shaders/closure_type_lib.glsl

@@ -49,7 +49,7 @@ struct Closure {
 #ifndef GPU_METAL
 /* Prototype */
 Closure nodetree_exec();
-vec4 closure_to_rgba(Closure);
+vec4 closure_to_rgba(Closure cl);
 void output_aov(vec4 color, float value, uint hash);
 vec3 coordinate_camera(vec3 P);
 vec3 coordinate_screen(vec3 P);

source/blender/draw/engines/eevee/shaders/volumetric_vert.glsl

@@ -57,3 +57,23 @@ float F_eta(float a, float b)
 {
   return 0.0;
 }
+
+vec3 coordinate_camera(vec3 P)
+{
+  return vec3(0.0);
+}
+
+vec3 coordinate_screen(vec3 P)
+{
+  return vec3(0.0);
+}
+
+vec3 coordinate_reflect(vec3 P, vec3 N)
+{
+  return vec3(0.0);
+}
+
+vec3 coordinate_incoming(vec3 P)
+{
+  return vec3(0.0);
+}