lightningd: free htlc maps on exit.

Direct leak of 16 byte(s) in 1 object(s) allocated from:
    #0 0x7ff02889063e in calloc (/lib/x86_64-linux-gnu/libasan.so.5+0x10c63e)
    #1 0x555ce2ad8d2e in htable_default_alloc ccan/ccan/htable/htable.c:19
    #2 0x555ce2ad9698 in double_table ccan/ccan/htable/htable.c:226
    #3 0x555ce2ad9b62 in htable_add_ ccan/ccan/htable/htable.c:331
    #4 0x555ce2a638e4 in htlc_in_map_add lightningd/htlc_end.h:113
    #5 0x555ce2a63beb in connect_htlc_in lightningd/htlc_end.c:39
    #6 0x555ce2a85cbc in channel_added_their_htlc lightningd/peer_htlcs.c:1382
    #7 0x555ce2a860e1 in peer_got_commitsig lightningd/peer_htlcs.c:1466
    #8 0x555ce2a5db04 in channel_msg lightningd/channel_control.c:228
    #9 0x555ce2a8d393 in sd_msg_read lightningd/subd.c:474
    #10 0x555ce2ada157 in next_plan ccan/ccan/io/io.c:59
    #11 0x555ce2adacd4 in do_plan ccan/ccan/io/io.c:407
    #12 0x555ce2adad12 in io_ready ccan/ccan/io/io.c:417
    #13 0x555ce2adcd67 in io_loop ccan/ccan/io/poll.c:445
    ElementsProject#14 0x555ce2a67c66 in io_loop_with_timers lightningd/io_loop_with_timers.c:24
    ElementsProject#15 0x555ce2a6e56b in main lightningd/lightningd.c:822
    ElementsProject#16 0x7ff028242b6a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x26b6a)

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/lightningd.c

@@ -838,6 +838,10 @@ int main(int argc, char *argv[])
 	free_unreleased_txs(ld->wallet);
 	db_commit_transaction(ld->wallet->db);
 
+	/* Clean our our HTLC maps, since they use malloc. */
+	htlc_in_map_clear(&ld->htlcs_in);
+	htlc_out_map_clear(&ld->htlcs_out);
+
 	remove(ld->pidfile);
 
 	/* FIXME: pay can have children off tmpctx which unlink from