Exit gracefully on ^D on control-console

[miodvallat]

Fixes: #1694

Short description

This changes DynListener to register the "quit" function separately from other functions, and then pretend this function name has been typed when the file descriptor gets closed.

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[coveralls]

Pull Request Test Coverage Report for Build 12790835357

Details

• 7 of 19 (36.84%) changed or added relevant lines in 2 files are covered.
• 100 unchanged lines in 11 files lost coverage.
• Overall coverage decreased (-0.03%) to 64.873%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pdns/auth-main.cc	1	6	16.67%
pdns/dynlistener.cc	6	13	46.15%

Files with Coverage Reduction	New Missed Lines	%
pdns/dynlistener.cc	1	37.62%
pdns/recursordist/aggressive_nsec.cc	2	66.39%
pdns/ws-auth.cc	2	80.8%
pdns/recursordist/test-syncres_cc2.cc	3	88.85%
pdns/packethandler.cc	3	72.44%
pdns/remote_logger.cc	3	54.26%
pdns/recursordist/rec-tcp.cc	10	66.07%
pdns/recursordist/taskqueue.cc	11	34.15%
pdns/recursordist/syncres.cc	14	80.07%
modules/lmdbbackend/lmdbbackend.cc	17	72.91%

Totals
Change from base Build 12766545506:	-0.03%
Covered Lines:	126310
Relevant Lines:	163852

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💛 - Coveralls