DwarfDebug.h - remove unnecessary forward declarations. NFC.

We include their headers already.

Author: RKSimon

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -49,7 +49,6 @@ namespace llvm {
 
 class AsmPrinter;
 class ByteStreamer;
-class DebugLocEntry;
 class DIE;
 class DwarfCompileUnit;
 class DwarfExpression;
@@ -59,7 +58,6 @@ class LexicalScope;
 class MachineFunction;
 class MCSection;
 class MCSymbol;
-class MDNode;
 class Module;
 
 //===----------------------------------------------------------------------===//