rename module to better reflect its purpose

Author: the8472

library/alloc/src/vec/source_iter_marker.rs renamed to library/alloc/src/vec/in_place_collect.rs

@@ -108,7 +108,7 @@ use self::is_zero::IsZero;
 mod is_zero;
 
 #[cfg(not(no_global_oom_handling))]
-mod source_iter_marker;
+mod in_place_collect;
 
 mod partial_eq;