Add initial integrated assembler w/ some Xmm ops.

src/IceInst.h

Index: src/IceInst.h
diff --git a/src/IceInst.h b/src/IceInst.h
index cf507e67cc0ef83bf5c3cbe8c34ac3a2c8d81625..a1b9f100d53b142874293049eb0bb5db2f21e75b 100644
--- a/src/IceInst.h
+++ b/src/IceInst.h
@@ -108,6 +108,7 @@ public:
   // instruction results in a single native instruction.
   virtual uint32_t getEmitInstCount() const { return 0; }
   virtual void emit(const Cfg *Func) const;
+  virtual void emitIAS(const Cfg *Func) const;
   virtual void dump(const Cfg *Func) const;
   virtual void dumpExtras(const Cfg *Func) const;
   void dumpDecorated(const Cfg *Func) const;