Simplifiy code using return value of erase().

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182506 91177308-0d34-0410-b5e6-96231b3b80d8

lib/StaticAnalyzer/Core/BugReporter.cpp

@@ -2017,10 +2017,8 @@ static void removePunyEdges(PathPieces &path,
       continue;
 
     if (abs(startCol - endCol) <= 2) {
-      PathPieces::iterator PieceToErase = I;
-      ++I;
+      I = path.erase(I);
       erased = true;
-      path.erase(PieceToErase);
       continue;
     }
   }