Further speedups to icu compilation, it is faster to run the
pre-generated configure scripts.
Ensure that the native protobuf installation only generates the required
libraries and binaries.
Disable qt compilation when running travis on windows. Qt is used for
lrelease, the travis recipe instead usese the a local installation of
lrelease.
Remove various packages and options from the travis recipe.
Update Readline to version 8.0. The previously used url 404'd sometimes,
use the official gnu ftp server instead.
Remove unused cmake config.
f0fc4064a0