multimedia/vlc: Prepare for Taglib 2.x

Backport several upstream commits to fix the build with taglib 2.x. [1]

Disable some compiler warnings that bloat the build log to the point
where it is barely readable.

Toggle the svgdec plugin in the LIBRSVG2 option to fix dependency issues
on live systems if it is set to off and the required dependencies are
auto-detected.

PR: 276677 [1]