Rename OptimizationDiagnosticInfo.* to OptimizationRemarkEmitter.*

Sync it up with the name of the class actually defined here.  This has been
bothering me for a while...

llvm-svn: 315249
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index a49da3a..2fb43fe 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -29,7 +29,7 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/Loads.h"
 #include "llvm/Analysis/LoopInfo.h"
-#include "llvm/Analysis/OptimizationDiagnosticInfo.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/IR/Argument.h"
 #include "llvm/IR/Attributes.h"