Fix for unwanted particle re-distribution happening due to memory optimization

The issue was caused by memory optimization marking particle system to recalc,
and because of the way how particle flags works it was possible that it'll
cause particle's re-distribution. Now this memory optimization will act the
same as loading the file.

This commit appears to be safe according to our render farm and is safe to
be included into final release.

source/blender/blenkernel/intern/object.c

@@ -363,6 +363,7 @@ void BKE_object_free_caches(Object *object)
 				psmd->dm->needsFree = 1;
 				psmd->dm->release(psmd->dm);
 				psmd->dm = NULL;
+				psmd->flag |= eParticleSystemFlag_file_loaded;
 				update_flag |= OB_RECALC_DATA;
 			}
 		}