This change fixes an unstable unit test and it was okayed on jabber.

    Merge branch 'trac5325' and added rules for files
    missed in asiolink:

src/lib/asiolink/Makefile.am
    +libkea_asiolink_la_SOURCES += io_acceptor.h
    +libkea_asiolink_la_SOURCES += unix_domain_socket_acceptor.h
    +libkea_asiolink_la_SOURCES += unix_domain_socket_endpoint.h

src/bin/d2/Makefile.am
    Added EXTRA_DIST rule for d2_parser.yy

This is trivial fix which I am committing on my discretion.

Also, when timeout occurs in control channel connection, all async tasks
are cancelled.