configure: Add support for GeoIP without pkg-config

If libgeoip is installed without a pkg-config data file, then fall
back to GEOIP_LIBS and GEOIP_CFLAGS, if set.

On systems that do not have the pkg-config data file for libgeoip,
running configure with GEOIP_LIBS and GEOIP_CFLAGS appropriately set,
along with --with-geoip, will enable the module.

Reported-by: Peter Czanik <czanik@balabit.hu>
Signed-off-by: Gergely Nagy <algernon@balabit.hu>
travis: Simplify the config

We only need one apt-get install line, and no template for the IRC
notifications, the default is good enough.

Signed-off-by: Gergely Nagy <algernon@balabit.hu>
Make it possible to link crypto stuff directly into libsyslog-ng

There's been a long desire to be able to link libsyslog-ng-crypto
directly into libsyslog-ng, if so desired. To accomplish that, we
introduce a --with-embedded-crypto option to configure, which in turn
produces a WITH_EMBEDDED_CRYPTO automake conditional.

If that conditional is set, then the sources of libsyslog-ng-crypto
get appended to the libsyslog-ng sources, and -crypto is not built. In
the non-embedded case CRYPTO_LIBS will be set to
${top_builddir}/lib/libsyslog-ng-crypto.la, otherwise it will be
empty. All users of the -crypto module (afsocket, dbparser &
cryptofuns) have been updated to use $(CRYPTO_LIBS) instead of
hard-coding libsyslog-ng-crypto.la.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>