Set x86 FPU precision to 64-bit for MinGW. Original patch by Jonathan Liu <net147@gmail.com>.

src/win32-headers.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 45 matching lines @@
 #include <windows.h>
 
 #ifdef V8_WIN32_HEADERS_FULL
 #include <time.h>  // For LocalOffset() implementation.
 #include <mmsystem.h>  // For timeGetTime().
 #ifdef __MINGW32__
 // Require Windows XP or higher when compiling with MinGW. This is for MinGW
 // header files to expose getaddrinfo.
 #undef _WIN32_WINNT
 #define _WIN32_WINNT 0x501
+#include <float.h>  // For _controlfp().
 #endif  // __MINGW32__
 #if !defined(__MINGW32__) || defined(__MINGW64_VERSION_MAJOR)
 #include <dbghelp.h>  // For SymLoadModule64 and al.
 #include <errno.h>  // For STRUNCATE
 #endif  // !defined(__MINGW32__) || defined(__MINGW64_VERSION_MAJOR)
 #include <limits.h>  // For INT_MAX and al.
 #include <tlhelp32.h>  // For Module32First and al.
 
 // These additional WIN32 includes have to be right here as the #undef's below
 // makes it impossible to have them elsewhere.
 #include <winsock2.h>
 #include <ws2tcpip.h>
 #ifndef __MINGW32__
 #include <wspiapi.h>
 #endif  // __MINGW32__
-#include <process.h>  // for _beginthreadex()
+#include <process.h>  // For _beginthreadex().
 #include <stdlib.h>
 #endif  // V8_WIN32_HEADERS_FULL
 
 #undef VOID
 #undef DELETE
 #undef IN
 #undef THIS
 #undef CONST
 #undef NAN
 #undef TRUE
 #undef FALSE
 #undef UNKNOWN
 #undef NONE
 #undef ANY
 #undef IGNORE
 #undef GetObject
 #undef CreateMutex
 #undef CreateSemaphore