Delete unused argument in AArch64MCInstLower constructor: it doesn't
use Mangler, and Mangler is in fact not even created when AArch64MCInstLower
is constructed.

This bug is reported by UBSan.

llvm-svn: 216030
diff --git a/llvm/lib/Target/AArch64/AArch64MCInstLower.cpp b/llvm/lib/Target/AArch64/AArch64MCInstLower.cpp
index 75a17b9..e57b0f4 100644
--- a/llvm/lib/Target/AArch64/AArch64MCInstLower.cpp
+++ b/llvm/lib/Target/AArch64/AArch64MCInstLower.cpp
@@ -25,8 +25,7 @@
 #include "llvm/Target/TargetMachine.h"
 using namespace llvm;
 
-AArch64MCInstLower::AArch64MCInstLower(MCContext &ctx, Mangler &mang,
-                                       AsmPrinter &printer)
+AArch64MCInstLower::AArch64MCInstLower(MCContext &ctx, AsmPrinter &printer)
     : Ctx(ctx), Printer(printer), TargetTriple(printer.getTargetTriple()) {}
 
 MCSymbol *