Fix warnings trivial warnings.

Fix warnings about:
 . Unused variables
 . format mismatch in printf/scanf format string and arguments
 . Missing parenthesis around assignment as truth values
 . Clang warnings anout unknown GCC pragma

usr.sbin/mtree/create.c

@@ -317,7 +317,9 @@ statd(FTS *t, FTSENT *parent, uid_t *puid, gid_t *pgid, mode_t *pmode,
 	gid_t sgid;
 	uid_t suid;
 	mode_t smode;
+#if !defined(__minix)
 	u_long sflags = 0;
+#endif /* !defined(__minix) */
 	const char *name = NULL;
 	gid_t savegid;
 	uid_t saveuid;