[analyzer]RetainCount: Fix an autorelease related false positive.

The Cnt variable is adjusted (incremented) for simplification of
checking logic. The increment should not be stored in the state.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174104 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp b/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
index e731e03..533d0b8 100644
--- a/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp
@@ -3487,7 +3487,7 @@
       else
         V = V ^ RefVal::NotOwned;
     } else {
-      V.setCount(Cnt - ACnt);
+      V.setCount(V.getCount() - ACnt);
       V.setAutoreleaseCount(0);
     }
     return setRefBinding(state, Sym, V);