Make gyp work with Cygwin

src/platform.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 73 matching lines @@
     // If the number is halfway between two integers, round to the even one.
     intgr--;
   }
 #endif
   return intgr;
 }
 
 
 #endif  // _MSC_VER
 
+#ifndef __CYGWIN__
 // Random is missing on both Visual Studio and MinGW.
 int random();
+#endif
 
 #endif  // WIN32
 
 #include "atomicops.h"
 #include "lazy-instance.h"
 #include "platform-tls.h"
 #include "sampler.h"
 #include "utils.h"
 #include "v8globals.h"
 
@@ skipping 610 matching lines @@
   static uint16_t HToN(uint16_t value);
   static uint16_t NToH(uint16_t value);
   static uint32_t HToN(uint32_t value);
   static uint32_t NToH(uint32_t value);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_