Remove unused private member variables found by clang's new -Wunused-private-field.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158086 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/ARCMigrate/TransGCCalls.cpp b/lib/ARCMigrate/TransGCCalls.cpp
index 1be9020..cd90343 100644
--- a/lib/ARCMigrate/TransGCCalls.cpp
+++ b/lib/ARCMigrate/TransGCCalls.cpp
@@ -20,13 +20,12 @@
 class GCCollectableCallsChecker :
                          public RecursiveASTVisitor<GCCollectableCallsChecker> {
   MigrationContext &MigrateCtx;
-  ParentMap &PMap;
   IdentifierInfo *NSMakeCollectableII;
   IdentifierInfo *CFMakeCollectableII;
 
 public:
-  GCCollectableCallsChecker(MigrationContext &ctx, ParentMap &map)
-    : MigrateCtx(ctx), PMap(map) {
+  GCCollectableCallsChecker(MigrationContext &ctx)
+    : MigrateCtx(ctx) {
     IdentifierTable &Ids = MigrateCtx.Pass.Ctx.Idents;
     NSMakeCollectableII = &Ids.get("NSMakeCollectable");
     CFMakeCollectableII = &Ids.get("CFMakeCollectable");
@@ -78,7 +77,6 @@
 } // anonymous namespace
 
 void GCCollectableCallsTraverser::traverseBody(BodyContext &BodyCtx) {
-  GCCollectableCallsChecker(BodyCtx.getMigrationContext(),
-                            BodyCtx.getParentMap())
+  GCCollectableCallsChecker(BodyCtx.getMigrationContext())
                                             .TraverseStmt(BodyCtx.getTopStmt());
 }