[lld] Do not include StringSwitch.h (NFC)

Author: kazutakahirata

lld/tools/lld/lld.cpp

@@ -30,7 +30,6 @@
 #include "lld/Common/Memory.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringSwitch.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/CrashRecoveryContext.h"