Add MI-Sched support for x86 macro fusion.

This is an awful implementation of the target hook. But we don't have
abstractions yet for common machine ops, and I don't see any quick way
to make it table-driven.

llvm-svn: 184664
diff --git a/llvm/lib/Target/X86/X86InstrInfo.h b/llvm/lib/Target/X86/X86InstrInfo.h
index f2f47ef..a0d1ba7 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.h
+++ b/llvm/lib/Target/X86/X86InstrInfo.h
@@ -339,6 +339,9 @@
                                        int64_t Offset1, int64_t Offset2,
                                        unsigned NumLoads) const;
 
+  virtual bool shouldScheduleAdjacent(MachineInstr* First,
+                                      MachineInstr *Second) const LLVM_OVERRIDE;
+
   virtual void getNoopForMachoTarget(MCInst &NopInst) const;
 
   virtual