paths.h: remove cruft

a research in debian codesearch and grepping over the pkgsrc
directory tree have shown that these macros are all either unused,
or defined by programs in case they need them.

include/paths.h

@@ -6,27 +6,18 @@
 
 #define	_PATH_BSHELL	"/bin/sh"
 #define	_PATH_CONSOLE	"/dev/console"
-#define	_PATH_CSHELL	"/bin/csh"
-#define	_PATH_DEVDB	"/var/run/dev.db"
 #define	_PATH_DEVNULL	"/dev/null"
-#define	_PATH_DRUM	"/dev/drum"
-#define	_PATH_GSHADOW	"/etc/gshadow"
 #define	_PATH_KLOG	"/proc/kmsg"
-#define	_PATH_KMEM	"/dev/kmem"
 #define	_PATH_LASTLOG	"/var/log/lastlog"
 #define	_PATH_MAILDIR	"/var/mail"
 #define	_PATH_MAN	"/usr/share/man"
-#define	_PATH_MEM	"/dev/mem"
 #define	_PATH_MNTTAB	"/etc/fstab"
 #define	_PATH_MOUNTED	"/etc/mtab"
 #define	_PATH_NOLOGIN	"/etc/nologin"
-#define	_PATH_PRESERVE	"/var/lib"
-#define	_PATH_RWHODIR	"/var/spool/rwho"
 #define	_PATH_SENDMAIL	"/usr/sbin/sendmail"
 #define	_PATH_SHADOW	"/etc/shadow"
 #define	_PATH_SHELLS	"/etc/shells"
 #define	_PATH_TTY	"/dev/tty"
-#define	_PATH_UNIX	"/boot/vmlinux"
 #define _PATH_UTMP	"/dev/null/utmp"
 #define	_PATH_VI	"/usr/bin/vi"
 #define _PATH_WTMP	"/dev/null/wtmp"