Use fast_sqrt instead of std::sqrt in simulators.

src/ppc/simulator-ppc.cc

Index: src/ppc/simulator-ppc.cc
diff --git a/src/ppc/simulator-ppc.cc b/src/ppc/simulator-ppc.cc
index 0d10153790b7c761b09a304ade49493598760441..34c35d613e6ff6dfa78acbc78612aeb6a785d01d 100644
--- a/src/ppc/simulator-ppc.cc
+++ b/src/ppc/simulator-ppc.cc
@@ -2613,7 +2613,7 @@ void Simulator::ExecuteExt4(Instruction* instr) {
       int frt = instr->RTValue();
       int frb = instr->RBValue();
       double frb_val = get_double_from_d_register(frb);
-      double frt_val = std::sqrt(frb_val);
+      double frt_val = fast_sqrt(frb_val);
       set_d_register_from_double(frt, frt_val);
       return;
     }