fix(vulkan): only PostFX_NotifyPostPipelinesRebuilt after real post rebuild

vk_update_post_process_pipelines could call PostFX_Notify when vk.fboActive
was false, clearing bloom/SSAO/SMAA modified flags without creating pipelines.
Run notify only inside the vk.fboActive block.

Co-authored-by: Tim Fox <timfox@outlook.com>

Author: cursoragent

src/renderers/vulkan/vk_post_process_refresh.c

@@ -68,6 +68,6 @@ void vk_update_post_process_pipelines( void )
 			vk_create_post_process_pipeline( 13, postWidth, postHeight );
 		}
 		vk_create_atmosphere_pipeline();
+		PostFX_NotifyPostPipelinesRebuilt();
 	}
-	PostFX_NotifyPostPipelinesRebuilt();
 }