Adds whitespace

Author: bkchr

src/librustc_mir/monomorphize/collector.rs

@@ -194,7 +194,7 @@ use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::hir::map as hir_map;
 use rustc::hir::def_id::DefId;
 use rustc::middle::const_val::ConstVal;
-use rustc::middle::lang_items::{ExchangeMallocFnLangItem,StartFnLangItem};
+use rustc::middle::lang_items::{ExchangeMallocFnLangItem, StartFnLangItem};
 use rustc::traits;
 use rustc::ty::subst::{Substs, Kind};
 use rustc::ty::{self, TypeFoldable, Ty, TyCtxt};