fix defines for openbsd - build fails without them:

src/base/macros.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BASE_MACROS_H_
 #define V8_BASE_MACROS_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 315 matching lines @@
 # else
 #  define V8_INTPTR_C(x)  (x)
 #  define V8_PTR_PREFIX   ""
 # endif  // V8_HOST_ARCH_64_BIT
 #elif V8_CC_MINGW64
 # define V8_UINT64_C(x)   (x ## ULL)
 # define V8_INT64_C(x)    (x ## LL)
 # define V8_INTPTR_C(x)   (x ## LL)
 # define V8_PTR_PREFIX    "I64"
 #elif V8_HOST_ARCH_64_BIT
-# if V8_OS_MACOSX
+# if V8_OS_MACOSX || V8_OS_OPENBSD
 #  define V8_UINT64_C(x)   (x ## ULL)
 #  define V8_INT64_C(x)    (x ## LL)
 # else
 #  define V8_UINT64_C(x)   (x ## UL)
 #  define V8_INT64_C(x)    (x ## L)
 # endif
 # define V8_INTPTR_C(x)   (x ## L)
 # define V8_PTR_PREFIX    "l"
 #else
 # define V8_UINT64_C(x)   (x ## ULL)
@@ skipping 62 matching lines @@
 }
 
 template <>
 inline bool is_fundamental<uint8_t>() {
   return true;
 }
 }
 }  // namespace v8::base
 
 #endif   // V8_BASE_MACROS_H_