Looks like we woke one of the startup io_loops early, and thus
we thought we'd finished connectd_activate and we hadn't. This
caused us to use an uninitialized ld->announceable array, and
finally caused an assert fail in the main loop.
Make *every* loop assert that it was exited for the correct reason,
so if it happens again, we can maybe figure out what part of
the code to look at.
```
lightningd: lightningd/lightningd.c:1186: main: Assertion `io_loop_ret == ld' failed.
lightningd: FATAL SIGNAL 6 (version 4df66fa)
...
------------------------------- Valgrind errors --------------------------------
Valgrind error file: valgrind-errors.895509
==895509== Conditional jump or move depends on uninitialised value(s)
==895509== at 0x22C58E: to_tal_hdr_or_null (tal.c:184)
==895509== by 0x22D531: tal_bytelen (tal.c:637)
==895509== by 0x1F10B6: towire_gossipd_init (gossipd_wiregen.c:100)
==895509== by 0x13AC6E: gossip_init (gossip_control.c:254)
==895509== by 0x1497EC: main (lightningd.c:1090)
==895509==
```
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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