various header cleanups, some related to _BSD_SOURCE addition

there is no reason to avoid multiple identical macro definitions; this
is perfectly legal C, and even with the maximal warning options
enabled, gcc does not issue any warning for it.

include/sys/file.h

@@ -4,16 +4,16 @@
 extern "C" {
 #endif
 
-#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
-
 #define LOCK_SH	1
 #define LOCK_EX	2
 #define LOCK_NB	4
 #define LOCK_UN	8
 
-int flock(int, int);
+#define L_SET 0
+#define L_INCR 1
+#define L_XTND 2
 
-#endif
+int flock(int, int);
 
 #ifdef __cplusplus
 }