Fixes Android build by using C++ math header instead of C one.

runtime/vm/simulator_arm64.cc

Index: runtime/vm/simulator_arm64.cc
===================================================================
--- runtime/vm/simulator_arm64.cc	(revision 37827)
+++ runtime/vm/simulator_arm64.cc	(working copy)
@@ -2,7 +2,6 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-#include <math.h>  // for isnan.
 #include <setjmp.h>
 #include <stdlib.h>
 
@@ -2444,9 +2443,9 @@
 
 static float arm_reciprocal_sqrt_estimate(float a) {
   // From the ARM Architecture Reference Manual A2-87.
-  if (isinf(a) || (fabs(a) >= exp2f(126))) return 0.0;
+  if (std::isinf(a) || (fabs(a) >= exp2f(126))) return 0.0;

[koda, 2014/06/30 20:50:40]

It looks slightly odd to have only one of these in std:: (since we still use
float.h rather than cfloat), but I think that's acceptable.

[siva, 2014/06/30 20:59:34]

I agree too, it does seem odd.

I am wondering if it would be more readable to add a 'vm/math.h' file and in it
have:
#include <cmath>
#define isinf(val) std:isinf(val)
#define isnan(val) std::isnan(val)

[zra, 2014/06/30 20:59:44]

Yah, it does look strange, but hopefully it will mean less work when we pull the
STL out.

[zra, 2014/06/30 22:14:33]

Done.

   else if (a == 0.0) return INFINITY;
-  else if (isnan(a)) return a;
+  else if (std::isnan(a)) return a;
 
   uint32_t a_bits = bit_cast<uint32_t, float>(a);
   uint64_t scaled;
@@ -2495,9 +2494,9 @@
 
 static float arm_recip_estimate(float a) {
   // From the ARM Architecture Reference Manual A2-85.
-  if (isinf(a) || (fabs(a) >= exp2f(126))) return 0.0;
+  if (std::isinf(a) || (fabs(a) >= exp2f(126))) return 0.0;
   else if (a == 0.0) return INFINITY;
-  else if (isnan(a)) return a;
+  else if (std::isnan(a)) return a;
 
   uint32_t a_bits = bit_cast<uint32_t, float>(a);
   // scaled = '0011 1111 1110' : a<22:0> : Zeros(29)
@@ -2820,7 +2819,7 @@
   c_flag_ = false;
   v_flag_ = false;
 
-  if (isnan(vn_val) || isnan(vm_val)) {
+  if (std::isnan(vn_val) || std::isnan(vm_val)) {
     c_flag_ = true;
     v_flag_ = true;
   } else if (vn_val == vm_val) {