Fix taglib detection on Windows

Reviewers: mpyne

Reviewed By: mpyne

Differential Revision: https://phabricator.kde.org/D16525
2 jobs for Applications/19.04 in 9 minutes and 4 seconds (queued for 3 minutes and 14 seconds)
Status Job ID Name Coverage
  Build
passed #2262
freebsd
freebsd stable-kf5-qt5 qt5.12

00:03:18

passed #2261
linux stable-kf5-qt5 qt5.10

00:05:45

2.0%