support _BSD_SOURCE feature test macro

patch by Isaac Dunham. matched closely (maybe not exact) to glibc's
idea of what _BSD_SOURCE should make visible.

include/fcntl.h

@@ -80,12 +80,24 @@ int posix_fallocate(int, off_t, off_t);
 #define S_IRWXO 0007
 #endif
 
-#ifdef _GNU_SOURCE
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
 #define FAPPEND O_APPEND
 #define FFSYNC O_FSYNC
 #define FASYNC O_ASYNC
 #define FNONBLOCK O_NONBLOCK
 #define FNDELAY O_NDELAY
+
+#ifndef F_OK
+#define F_OK 0
+#define R_OK 4
+#define W_OK 2
+#define X_OK 1
+#define F_ULOCK 0
+#define F_LOCK  1
+#define F_TLOCK 2
+#define F_TEST  3
+int lockf(int, int, off_t);
+#endif
 #endif
 
 #ifdef _LARGEFILE64_SOURCE