[qt5-build.eclass] Introduce qt_use_compile_test().
[dev-qt/qtwayland:5] Use qt_use_compile_test.

Package-Manager: portage-2.2.11
[dev-qt/qtmultimedia:5] Fix automagic deps, add opengl and widgets USE flags.

Based on pull request #67 by xhochy. Fixes bug #517532.

Package-Manager: portage-2.2.11