GitLab

MRG: fixes and tests for builds

* Added Andrew Murray's changes to the URLs, http -> https.
* Fixed the `suppress` utility to work correctly with set -e; it was previously
  swallowing errors, concealing real build failures, in the tests.
* Fixed some build recipe failures revealed by the fixes to `suppress`.
* Added BUILD_PREFIX to pkg-config PATH, to promote built packages before
  system packages.
* Disabled the lzo build test, pending fixes to clang build by author.
* Updated lzo version to latest.