- libknot-int exports all symbols
- pkg-config is updated to make the change transparent

Enables libknot headers and .pc installation, allowing use of libknot in
external projects.

* install_headers:
  pkg-config: use PKG_INSTALLDIR [review]
  Makefile: fix broken linking of systemd [review]
  Makefile: clean duplicate headers [review]
  pkg-config: don't publish already prefixed include path
  makefile: generate pkg-config file for libknot, versioning
  makefile: merge libknotcs -> libknot
  makefile: clean duplicates

As of now, the version of the library is consistent with the release.

* improve-signal-handling:
  knotd: handle control interrupts atomically
  review: bool signal variables
  fdset: require pselect(), remove unsafe compat implementation
  knotd: reset umask() when starting
  knotd: properly set signal blocking for new threads
  knotd: fix previously broken signal blocking
  knotd: setup signal at once place
  knotd: remove forced stop from signal handler

Merge request !308

Lubos Slovak authored 10 years ago and Jan Včelák committed 10 years ago

- Test response with a long CNAME loop.
- Some queries in basic/query test did not have the zone name
  appended, resulting in bogus answers (REFUSED). Not visible,
  because the responses are only compared to ones from Bind.

TODO: Comparison with Bind should be replaced by checks for
      particular requirements for the response.

Daniel Salzman authored 10 years ago and Jan Včelák committed 10 years ago

The previous value (4 sec) extended ixfr/from_differences execution
time by 40 minutes!

Active signal mask is inherited by new threads. Therefore, control
signals used by the main thread had to be blocked at the moment, when
new threds are created.

The former mask used to block signals was empty and had no effect.

The signals are blocked during server shutdown. Therefore the signal
handler could not be called twice.

Improve structure names

See merge request !307