gnu: libmygpo-qt: Fix Qt 5.11 build.

The update to Qt 5.11.0 broke libmygpo-qt. It turned it was using a deprecated
CMake function (qt5_use_moduldes).  Let's pick up two upstream patches that
fix the issue: https://github.com/gpodder/libmygpo-qt/pull/15



As mentioned in the the pull request, there is now a test failure but it looks
harmless.

* gnu/packages/patches/libmygpo-qt-fix-qt-5.11.patch,
gnu/packages/patches/libmygpo-qt-missing-qt5-modules.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/music.scm (libmygpo-qt)[source]: Add patches.
[arguments]: Build tests but do not run them.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>