engine: move PARM_SKY_SPHERE handling out of engine to renderer, after all renderers might or might not support sky spheres

engine/client/cl_render.c

@@ -142,8 +142,6 @@ intptr_t CL_RenderGetParm( const int parm, const int arg, const qboolean checkRe
 		return 1;
 #endif
 		return 0;
-	case PARM_SKY_SPHERE:
-		return FBitSet( world.flags, FWORLD_SKYSPHERE ) && !FBitSet( world.flags, FWORLD_CUSTOM_SKYBOX );
 	case PARAM_GAMEPAUSED:
 		return cl.paused;
 	case PARM_CLIENT_INGAME:

ref/gl/gl_context.c

@@ -236,7 +236,7 @@ static int GL_RefGetParm( int parm, int arg )
 	case PARM_STENCIL_ACTIVE:
 		return glState.stencilEnabled;
 	case PARM_SKY_SPHERE:
-		return ENGINE_GET_PARM_( parm, arg ) && !tr.fCustomSkybox;
+		return FBitSet( tr.world->flags, FWORLD_SKYSPHERE ) && !FBitSet( tr.world->flags, FWORLD_CUSTOM_SKYBOX );
 	default:
 		return ENGINE_GET_PARM_( parm, arg );
 	}

ref/soft/r_context.c

@@ -171,7 +171,7 @@ static int GL_RefGetParm( int parm, int arg )
 	case PARM_STENCIL_ACTIVE:
 		return 0; //glState.stencilEnabled;
 	case PARM_SKY_SPHERE:
-		return ENGINE_GET_PARM_( parm, arg ) && !tr.fCustomSkybox;
+		return 0; // ref_soft doesn't support sky sphere
 	default:
 		return ENGINE_GET_PARM_( parm, arg );
 	}