Reduce number of available colors in RA by # of reserved

GRFs in fail safe

In fail safe RA, we reserve some number of GRFs to guarantee RA
termination. When GRFs are reserved, we must also reduce number of
available colors when determining color ordering.

Author: pratikashar

visa/GraphColor.cpp

@@ -6774,7 +6774,7 @@ void GraphColor::removeConstrained() {
 void GraphColor::determineColorOrdering() {
   numColor = 0;
   if (liveAnalysis.livenessClass(G4_GRF))
-    numColor = totalGRFRegCount;
+    numColor = totalGRFRegCount - reserveSpillGRFCount;
   else if (liveAnalysis.livenessClass(G4_ADDRESS))
     numColor = builder.getNumAddrRegisters();
   else if (liveAnalysis.livenessClass(G4_FLAG))