Bug 817267 - dirfd() is a macro on some BSDs, fix build there. r=yoric

dom/system/OSFileConstants.cpp

@@ -41,6 +41,11 @@
 #include "OSFileConstants.h"
 #include "nsIOSFileConstantsService.h"
 
+#if defined(__DragonFly__) || defined(__FreeBSD__) \
+  || defined(__NetBSD__) || defined(__OpenBSD__)
+#define __dd_fd dd_fd
+#endif
+
 /**
  * This module defines the basic libc constants (error numbers, open modes,
  * etc.) used by OS.File and possibly other OS-bound JavaScript libraries.
@@ -383,8 +388,8 @@ static dom::ConstantSpec gLibcProperties[] =
   { "OSFILE_OFFSETOF_DIRENT_D_TYPE", INT_TO_JSVAL(offsetof (struct dirent, d_type)) },
 #endif // defined(DT_UNKNOWN)
 
-  // Under MacOS X, |dirfd| is a macro rather than a function, so we
-  // need a little help to get it to work
+  // Under MacOS X and BSDs, |dirfd| is a macro rather than a
+  // function, so we need a little help to get it to work
 #if defined(dirfd)
   { "OSFILE_SIZEOF_DIR", INT_TO_JSVAL(sizeof (DIR)) },