more thread support, also add freebsd 5
diff --git a/include/u.h b/include/u.h
index c1ca033..595f91d 100644
--- a/include/u.h
+++ b/include/u.h
@@ -4,13 +4,14 @@
extern "C" {
#endif
+#define __BSD_VISIBLE 1 /* FreeBSD 5.x */
+#define __EXTENSIONS__ 1 /* SunOS */
#define _BSD_SOURCE 1
#define _SVID_SOURCE 1
#define _XOPEN_SOURCE 1000
#define _XOPEN_SOURCE_EXTENDED 1
#define _LARGEFILE64_SOURCE 1
#define _FILE_OFFSET_BITS 64
-#define __EXTENSIONS__ 1 /* SunOS */
#include <unistd.h>
#include <string.h>
@@ -43,34 +44,41 @@
# undef _NEEDULONG
# endif
# if defined(__Linux26__)
-# include <pthread.h>
-# define PLAN9_PTHREADS 1
+# define PLAN9PORT_USING_PTHREADS 1
# endif
-#endif
-#if defined(__sun__)
+#elif defined(__sun__)
# include <sys/types.h>
# undef _NEEDUSHORT
# undef _NEEDUINT
# undef _NEEDULONG
-# include <pthread.h>
-# define PLAN9_PTHREADS
-#endif
-#if defined(__FreeBSD__)
+# define PLAN9PORT_USING_PTHREADS 1
+#elif defined(__FreeBSD__)
# include <sys/types.h>
# if !defined(_POSIX_SOURCE)
# undef _NEEDUSHORT
# undef _NEEDUINT
# endif
-#endif
-#if defined(__APPLE__)
+# if defined(__FreeBSD5__)
+# define PLAN9PORT_USING_PTHREADS 1
+# endif
+#elif defined(__APPLE__)
# include <sys/types.h>
# undef _NEEDUSHORT
# undef _NEEDUINT
# define _NEEDLL 1
-# include <pthread.h>
-# define PLAN9_PTHREADS
+# define PLAN9PORT_USING_PTHREADS 1
+#else
+ /* No idea what system this is -- try some defaults */
+# define PLAN9PORT_USING_PTHREADS 1
#endif
+#ifndef O_DIRECT
+#define O_DIRECT 0
+#endif
+
+#ifdef PLAN9PORT_USING_PTHREADS
+#include <pthread.h>
+#endif
typedef signed char schar;
typedef unsigned int u32int;
