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

runtime/vm/simulator_mips.cc

Index: runtime/vm/simulator_mips.cc
===================================================================
--- runtime/vm/simulator_mips.cc	(revision 37827)
+++ runtime/vm/simulator_mips.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>
 
@@ -1593,7 +1592,7 @@
       case COP1_C_UN: {
         ASSERT(instr->FormatField() == FMT_D);  // Only D supported.
         ASSERT(instr->FdField() == F0);
-        set_fcsr_bit(fcsr_cc, isnan(fs_val) || isnan(ft_val));
+        set_fcsr_bit(fcsr_cc, std::isnan(fs_val) || std::isnan(ft_val));
         break;
       }
       case COP1_C_EQ: {
@@ -1606,7 +1605,7 @@
         ASSERT(instr->FormatField() == FMT_D);  // Only D supported.
         ASSERT(instr->FdField() == F0);
         set_fcsr_bit(fcsr_cc,
-            (fs_val == ft_val) || isnan(fs_val) || isnan(ft_val));
+            (fs_val == ft_val) || std::isnan(fs_val) || std::isnan(ft_val));
         break;
       }
       case COP1_C_OLT: {
@@ -1619,7 +1618,7 @@
         ASSERT(instr->FormatField() == FMT_D);  // Only D supported.
         ASSERT(instr->FdField() == F0);
         set_fcsr_bit(fcsr_cc,
-            (fs_val < ft_val) || isnan(fs_val) || isnan(ft_val));
+            (fs_val < ft_val) || std::isnan(fs_val) || std::isnan(ft_val));
         break;
       }
       case COP1_C_OLE: {
@@ -1632,7 +1631,7 @@
         ASSERT(instr->FormatField() == FMT_D);  // Only D supported.
         ASSERT(instr->FdField() == F0);
         set_fcsr_bit(fcsr_cc,
-            (fs_val <= ft_val) || isnan(fs_val) || isnan(ft_val));
+            (fs_val <= ft_val) || std::isnan(fs_val) || std::isnan(ft_val));
         break;
       }
       case COP1_CVT_D: {
@@ -1668,8 +1667,8 @@
           case FMT_D: {
             double fs_dbl = get_fregister_double(instr->FsField());
             int32_t fs_int;
-            if (isnan(fs_dbl) || isinf(fs_dbl) || (fs_dbl > INT_MAX) ||
-                (fs_dbl < INT_MIN)) {
+            if (std::isnan(fs_dbl) || std::isinf(fs_dbl) ||
+                (fs_dbl > INT_MAX) || (fs_dbl < INT_MIN)) {
               fs_int = INT_MIN;
             } else {
               fs_int = static_cast<int32_t>(fs_dbl);