Fail the build early if xmllint is not available
Summary:
xmllint is required later anyway, and kio_help has the check.
BUG: 376246
Test Plan: If xmllint is not available, compilation fails in the cmake phase.
Reviewers: winterz
Reviewed By: winterz
Subscribers: Frameworks, Documentation
Tags: Frameworks, Documentation
Differential Revision: https://phabricator.kde.org/D4558