FreeBSD: Fix semaphore alignment

src/base/platform/semaphore.cc

 // Copyright 2013 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.
 
 #include "src/base/platform/semaphore.h"
 
 #if V8_OS_MACOSX
 #include <mach/mach_init.h>
 #include <mach/task.h>
 #endif
@@ skipping 59 matching lines @@
   }
 }
 
 #elif V8_OS_POSIX
 
 Semaphore::Semaphore(int count) {
   // The sem_init() does not check for alignment of the native handle.
   // Unaligned native handle can later cause a failure in semaphore signal.
   // Check the alignment here to catch the failure earlier.
   // Context: crbug.com/605349.
-#if V8_OS_AIX
-  // On aix sem_t is of type int
+#if V8_OS_AIX || V8_OS_FREEBSD
+  // On aix sem_t is of type int. On FreeBSD, it's a struct of 32 bits fields.
   const uintptr_t kSemaphoreAlignmentMask = sizeof(int) - 1;
 #else
   const uintptr_t kSemaphoreAlignmentMask = sizeof(void*) - 1;
 #endif
   CHECK_EQ(
       0, reinterpret_cast<uintptr_t>(&native_handle_) &
       kSemaphoreAlignmentMask);
   DCHECK(count >= 0);
   int result = sem_init(&native_handle_, 0, count);
   DCHECK_EQ(0, result);
@@ skipping 104 matching lines @@
       DCHECK(result == WAIT_OBJECT_0);
       return true;
     }
   }
 }
 
 #endif  // V8_OS_MACOSX
 
 }  // namespace base
 }  // namespace v8