Fix JSON serialization of ConstraintSolver statistics

Author: slavapestov

lib/Sema/CSSolver.cpp

@@ -28,19 +28,18 @@ using namespace constraints;
 // Constraint solver statistics
 //===----------------------------------------------------------------------===//
 #define DEBUG_TYPE "Constraint solver overall"
-#define JOIN(X,Y) JOIN2(X,Y)
 #define JOIN2(X,Y) X##Y
 STATISTIC(NumSolutionAttempts, "# of solution attempts");
 STATISTIC(TotalNumTypeVariables, "# of type variables created");
 
 #define CS_STATISTIC(Name, Description) \
-  STATISTIC(JOIN2(Overall,Name), Description);
+  STATISTIC(Overall##Name, Description);
 #include "ConstraintSolverStats.def"
 
 #undef DEBUG_TYPE
 #define DEBUG_TYPE "Constraint solver largest system"
 #define CS_STATISTIC(Name, Description) \
-  STATISTIC(JOIN2(Largest,Name), Description);
+  STATISTIC(Largest##Name, Description);
 #include "ConstraintSolverStats.def"
 STATISTIC(LargestSolutionAttemptNumber, "# of the largest solution attempt");