TGLexer.h - cleanup includes and forward declarations. NFC.

Replace ArrayRef.h with a forward declaration and include in ArrayRef.cpp
Remove SMLoc forward declaration as we already have to include SMLoc.h

Author: RKSimon

llvm/lib/TableGen/TGLexer.cpp

@@ -11,6 +11,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "TGLexer.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Config/config.h" // for strtoull()/strtoll() define

llvm/lib/TableGen/TGLexer.h

@@ -13,7 +13,6 @@
 #ifndef LLVM_LIB_TABLEGEN_TGLEXER_H
 #define LLVM_LIB_TABLEGEN_TGLEXER_H
 
-#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/DataTypes.h"
@@ -24,8 +23,8 @@
 #include <string>
 
 namespace llvm {
+template <typename T> class ArrayRef;
 class SourceMgr;
-class SMLoc;
 class Twine;
 
 namespace tgtok {