Reduce double set lookups by using the result of insert.

No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@192598 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/VTableBuilder.cpp b/lib/AST/VTableBuilder.cpp
index 027735d..045b7f1 100644
--- a/lib/AST/VTableBuilder.cpp
+++ b/lib/AST/VTableBuilder.cpp
@@ -3151,9 +3151,8 @@
     CharUnits NextBaseOffset;
     const CXXRecordDecl *NextLastVBase;
     if (I->isVirtual()) {
-      if (VisitedVBases.count(BaseDecl))
+      if (!VisitedVBases.insert(BaseDecl))
         continue;
-      VisitedVBases.insert(BaseDecl);
       NextBaseOffset = MostDerivedClassLayout.getVBaseClassOffset(BaseDecl);
       NextLastVBase = BaseDecl;
     } else {