Subzero: Don't bother printing stack/frame ptr as part of LiveIn/LiveOut.

The LiveIn and LiveOut register sets are printed for each basic block in -asm-verbose mode.  These sets would generally include the stack and/or frame pointer registers, which is just noise, so we suppress that.

BUG= none
R=jpp@chromium.org

Review URL: https://codereview.chromium.org/1399523003 .
diff --git a/src/IceTargetLowering.h b/src/IceTargetLowering.h
index f35983f..32fdc44 100644
--- a/src/IceTargetLowering.h
+++ b/src/IceTargetLowering.h
@@ -186,6 +186,7 @@
   virtual IceString getRegName(SizeT RegNum, Type Ty) const = 0;
 
   virtual bool hasFramePointer() const { return false; }
+  virtual SizeT getStackReg() const = 0;
   virtual SizeT getFrameOrStackReg() const = 0;
   virtual size_t typeWidthInBytesOnStack(Type Ty) const = 0;