allow static linking of libzip

[sanderland]

Probably not optimal, but it's a start :) Linking to a libzip.a compiled with

cmake .. -DLIBZIP_DO_INSTALL=0 -DBUILD_SHARED_LIBS=0 -DENABLE_BZIP2=0 -DENABLE_LZMA=0 -DENABLE_COMMONCRYPTO=0 -DENABLE_GNUTLS=0 -DENABLE_MBEDTLS=0 -DENABLE_OPENSSL=0 -DENABLE_WINDOWS_CRYPTO=0

appears to work. I could not convince find_library to nicely find this without manually specifying all the vars, so this is just an option to bypass the find_library on linux, as one can do anyway when the library isn't there.

One concern is the caching of these vars in cmake, which makes it hard to switch back.

Resulting exe: katago.zip

[hadim]

That would be nice to be able to link libzip to prevent errors such as error while loading shared libraries: libzip.so.5: cannot open shared object file: No such file or directory on Ubuntu machines.