Sort include directives

Upcoming revisions of isl require us to include header files explicitly, which
have previously been already transitively included. Before we add them, we sort
the existing includes.

Thanks to Chandler for sort_includes.py. A simple, but very convenient script.

llvm-svn: 236930
diff --git a/polly/lib/Support/SCEVValidator.cpp b/polly/lib/Support/SCEVValidator.cpp
index f1d9443..b06e8be 100644
--- a/polly/lib/Support/SCEVValidator.cpp
+++ b/polly/lib/Support/SCEVValidator.cpp
@@ -1,11 +1,10 @@
 
 #include "polly/Support/SCEVValidator.h"
 #include "polly/ScopInfo.h"
+#include "llvm/Analysis/RegionInfo.h"
 #include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Analysis/RegionInfo.h"
 #include "llvm/Support/Debug.h"
-
 #include <vector>
 
 using namespace llvm;