[C++11] More 'nullptr' conversion. In some cases just using a boolean check instead of comparing to nullptr.

llvm-svn: 206243
diff --git a/llvm/lib/Analysis/RegionPass.cpp b/llvm/lib/Analysis/RegionPass.cpp
index 12d7ca3..b29070a 100644
--- a/llvm/lib/Analysis/RegionPass.cpp
+++ b/llvm/lib/Analysis/RegionPass.cpp
@@ -31,8 +31,8 @@
   : FunctionPass(ID), PMDataManager() {
   skipThisRegion = false;
   redoThisRegion = false;
-  RI = NULL;
-  CurrentRegion = NULL;
+  RI = nullptr;
+  CurrentRegion = nullptr;
 }
 
 // Recurse through all subregions and all regions  into RQ.