Reg utility fix

Long ago in a galaxy far away, there was a trace compiler that
handled short code fragments with a small, sparse and variable
set of temp registers.  In that situation, doing linear reg
lookups wasn't terrible.  In the new world that has a fixed and
packed set of registers, a linear search is unnecessary, foolish
and wasteful.  [P.S. perf showed that roughly 25% of all
compilation time was spent doing register manipulation!]

Change-Id: I6f23d9f70367fb4139cc28a27fd9fdf8beffa270
diff --git a/src/compiler/codegen/arm/ArmRallocUtil.cc b/src/compiler/codegen/arm/ArmRallocUtil.cc
index 94852e3..ed8a5b2 100644
--- a/src/compiler/codegen/arm/ArmRallocUtil.cc
+++ b/src/compiler/codegen/arm/ArmRallocUtil.cc
@@ -322,3 +322,9 @@
     oatMarkInUse(cUnit, r1);
     return res;
 }
+
+extern RegisterInfo* oatGetRegInfo(CompilationUnit* cUnit, int reg)
+{
+    return FPREG(reg) ? &cUnit->regPool->FPRegs[reg & FP_REG_MASK]
+                      : &cUnit->regPool->coreRegs[reg];
+}