Various fixes for NBSD include.

This patch include various fixes to NBSD includes.

- unistd.h: Avoid different linkages on non-_NETBSD_SOURCE 
 compilation;
- stdlib.h: remove devname declaration.
- sys/select.h: Add _MINIX specific flags.
- limits.h: Add SYMLOOP_MAX and SYMLINK_MAX
- time.h: Fix CLOCKS_PER_SEC and remove BSD's timer_t, as it
  confuses minix own specific timers.
- utmp.h: Set Minix-specific paths and use Minix utmp format.
- param.h: Do not set BSD4_4, as this mostly means sa_len in
  struct sock_addr.
- arch/i386/include/param.h: include <machine/vmparam.h> to 
  add PAGE_SIZE and related macros, defined round_page() and
  trunc_page() for minix compatibility.

- dirent.h: remove DIRBLKSIZ and fix d_ino/d_fileno.
- sys/dir.h: ADD from existing includes and edit include
  conditions.
- sys/dirent.h: include <minix/dirent.h>, fix d_ino/d_fileno.

- sys/fd_set.h: set default FD_SETSIZE at __MINIX_OPENMAX, as 
  the default NetBSD value is too big and cause vfs to return
  an error.
- sys/cdefs.h: Always include <minix/ansi.h>

- minix/paths.h: Add Minix-specific paths.
- minix/dirent.h: ADD, keep only "direct" and "flex"definitions.
- minix/types.h: include <minix/ansi.h>

- sys/Makefile: add sys/dirent.h and statfs.h (forgot!)
- minix/Makefile: add minix/dirent.h

   nbsd_include/minix-port.patch updated accordingly.

nbsd_include/arch/i386/include/param.h

@@ -41,18 +41,6 @@
  * Machine dependent constants for Intel 386.
  */
 
-#ifdef _KERNEL
-#include <machine/cpu.h>
-#endif
-
-#ifndef _MINIX
-#define	_MACHINE	i386
-#define	MACHINE		"i386"
-#define	_MACHINE_ARCH	i386
-#define	MACHINE_ARCH	"i386"
-#define	MID_MACHINE	MID_I386
-#endif
-
 /*
  * Round p (pointer or byte index) up to a correctly-aligned value
  * for all data types (int, long, ...).   The result is u_int and
@@ -87,4 +75,13 @@
 #define	x86_btop(x)		((paddr_t)(x) >> PGSHIFT)
 #define	x86_ptob(x)		((paddr_t)(x) << PGSHIFT)
 
+#ifdef __minix
+/* Minix expect to find in this file PAGE_* defines. */
+#include <machine/vmparam.h>
+
+#define trunc_page(x) x86_trunc_page(x)
+#define round_page(x) x86_round_page(x)
+
+#endif
+
 #endif /* _I386_PARAM_H_ */