Use find_package for zlib

[elshize]

For some reason, if I use find_package to find zlib dependency within conan packages, it fails despite linking against the library:

/usr/bin/g++-7   -Wall -pedantic -fno-strict-aliasing -march=native  -O3   CMakeFiles/irk-warc.dir/irk-warc.cpp.o  -o ../bin/irk-warc -Wl,-rpath,/home/travis/.conan/data/zlib/1.2.11/conan/stable/package/5246c0bd84cb3855ffc2a458086a0813344953bf/lib:/home/travis/.conan/data/TBB/2018_U5/conan/stable/package/160b4bac5177b0f9a5f4857d00317fe0862a8a02/lib:/home/travis/.conan/data/streamvbyte/master/elshize/testing/package/6ae331b72e7e265ca2a3d1d8246faf73aa030238/lib:/home/travis/.conan/data/gumbo-parser/1.0/elshize/stable/package/6ae331b72e7e265ca2a3d1d8246faf73aa030238/lib: /home/travis/.conan/data/zlib/1.2.11/conan/stable/package/5246c0bd84cb3855ffc2a458086a0813344953bf/lib/libz.so -lpthread /usr/lib/x86_64-linux-gnu/libboost_iostreams.a /usr/lib/x86_64-linux-gnu/libboost_regex.a /usr/lib/x86_64-linux-gnu/libboost_filesystem.a /usr/lib/x86_64-linux-gnu/libboost_system.a /home/travis/.conan/data/fmt/5.1.0/bincrafters/stable/package/66c5327ebdcecae0a01a863939964495fa019a06/lib/libfmt.a /home/travis/.conan/data/TBB/2018_U5/conan/stable/package/160b4bac5177b0f9a5f4857d00317fe0862a8a02/lib/libtbb.so /home/travis/.conan/data/rax/master/elshize/testing/package/6ae331b72e7e265ca2a3d1d8246faf73aa030238/lib/librax.a /home/travis/.conan/data/streamvbyte/master/elshize/testing/package/6ae331b72e7e265ca2a3d1d8246faf73aa030238/lib/libstreamvbyte.so /home/travis/.conan/data/gumbo-parser/1.0/elshize/stable/package/6ae331b72e7e265ca2a3d1d8246faf73aa030238/lib/libgumbo.so

Check out Travis build for details: https://travis-ci.org/elshize/irkit/builds/449604806

[elshize]

Does it have something to do with zlib being built as shared library?

[elshize]

irk-warc is now commented out. Once this is resolved, it should be uncommented.