Avoid "Unknown command" messages when receiving getaddr on outbound c…

[rebroad]

…onnections.

Replaces #6344 and addresses concerns raised (i.e. now logs this exceptional event).

[sipa]

utACK

Tiny nit: can you use a less wide commit title? See http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html for example.

[laanwj]

utACK rebroad/bitcoin@d84ea1a

[MarcoFalke]

utACK d84ea1a

[kirkalx]

utACK.
Was looking at this code recently @rebroad and as I recall there were a few other similar situations there if you are looking for some more cleanups. Otherwise I'll put it on my TODO list :)

e.g.

    else if (strCommand == NetMsgType::HEADERS && !fImporting && !fReindex) // Ignore headers received while importing

[rebroad]

@sipa commit reworded

[MarcoFalke]

Could be tagged with "Needs backport"

[MarcoFalke]

Backported as part of #7938. Removing label 'Needs backport'.