Define _PATH_MKSNAP_FFS and use it in dump(8) instead of assuming

that mksnap_ffs(8) can be found using the current $PATH.

Reviewed by:	mckusick

include/paths.h

@@ -71,6 +71,7 @@
 #define	_PATH_MAN	"/usr/share/man"
 #define	_PATH_MDCONFIG	"/sbin/mdconfig"
 #define	_PATH_MEM	"/dev/mem"
+#define	_PATH_MKSNAP_FFS	"/sbin/mksnap_ffs"
 #define	_PATH_MOUNT	"/sbin/mount"
 #define	_PATH_NEWFS	"/sbin/newfs"
 #define	_PATH_NOLOGIN	"/var/run/nologin"

sbin/dump/main.c

@@ -321,8 +321,8 @@ main(int argc, char *argv[])
 
 			snprintf(snapname, sizeof snapname,
 			    "%s/.snap/dump_snapshot", mntpt);
-			snprintf(snapcmd, sizeof snapcmd,
-			    "mksnap_ffs %s %s", mntpt, snapname);
+			snprintf(snapcmd, sizeof snapcmd, "%s %s %s",
+			    _PATH_MKSNAP_FFS, mntpt, snapname);
 			unlink(snapname);
 			if (system(snapcmd) != 0)
 				errx(X_STARTUP, "Cannot create %s: %s\n",