MC] Provide an MCTargetOptions to implementors of MCAsmBackendCtorTy, NFC

Some targets, notably AArch64 for ILP32, have different relocation encodings
based upon the ABI. This is an enabling change, so a future patch can use the
ABIName from MCTargetOptions to chose which relocations to use. Tested using
check-llvm.

The corresponding change to clang is in: http://reviews.llvm.org/D16538

Patch by: Joel Jones

Differential Revision: https://reviews.llvm.org/D16213

llvm-svn: 276654
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
index e77a0dc..524b48b 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@@ -837,7 +837,8 @@
 MCAsmBackend *llvm::createX86_32AsmBackend(const Target &T,
                                            const MCRegisterInfo &MRI,
                                            const Triple &TheTriple,
-                                           StringRef CPU) {
+                                           StringRef CPU,
+                                           const MCTargetOptions &Options) {
   if (TheTriple.isOSBinFormatMachO())
     return new DarwinX86_32AsmBackend(T, MRI, CPU);
 
@@ -855,7 +856,8 @@
 MCAsmBackend *llvm::createX86_64AsmBackend(const Target &T,
                                            const MCRegisterInfo &MRI,
                                            const Triple &TheTriple,
-                                           StringRef CPU) {
+                                           StringRef CPU,
+                                           const MCTargetOptions &Options) {
   if (TheTriple.isOSBinFormatMachO()) {
     MachO::CPUSubTypeX86 CS =
         StringSwitch<MachO::CPUSubTypeX86>(TheTriple.getArchName())