Fix a bug where restore(8) segfaults while trying to restore on a

read-only FS.

Reviewed by:	audit silence
Approved by:	markm
MFC after:	2 weeks

sbin/restore/symtab.c

@@ -471,6 +471,7 @@ dumpsymtable(filename, checkpt)
 		fprintf(stderr, "fopen: %s\n", strerror(errno));
 		panic("cannot create save file %s for symbol table\n",
 			filename);
+		done(1);
 	}
 	clearerr(fd);
 	/*