Reduce duplicated hash map lookups.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162361 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 3adbc57..ff46bf0 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2631,7 +2631,7 @@
     
     for (unsigned I = 0, N = Mod->Imports.size(); I != N; ++I) {
       Module *Imported = Mod->Imports[I];
-      if (Visited.count(Imported))
+      if (!Visited.insert(Imported))
         continue;
       
       bool Acceptable = UnrestrictedWildcard;
@@ -2649,7 +2649,6 @@
       if (!Acceptable)
         continue;
       
-      Visited.insert(Imported);
       Stack.push_back(Imported);
     }
   }