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

runtime/platform/c99_support_win.h

Index: runtime/platform/c99_support_win.h
===================================================================
--- runtime/platform/c99_support_win.h	(revision 37827)
+++ runtime/platform/c99_support_win.h	(working copy)
@@ -26,6 +26,8 @@
 #define NAN \
     *reinterpret_cast<const double*>(&kQuietNaNMask)
 
+namespace std {
+
 static inline int isinf(double x) {
   return (_fpclass(x) & (_FPCLASS_PINF | _FPCLASS_NINF)) != 0;
 }
@@ -42,6 +44,8 @@
   }
 }
 
+}  // namespace std
+
 static inline double trunc(double x) {
   if (x < 0) {
     return ceil(x);