Push twines deeper into SourceMgr's error handling methods.

llvm-svn: 114847

llvm/tools/llvm-mc/Disassembler.cpp

@@ -24,6 +24,7 @@
 #include "llvm/Target/TargetRegistry.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/ADT/Twine.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/MemoryObject.h"
 #include "llvm/Support/raw_ostream.h"