mpv-plugin.eclass: recursive doins

Some plugins, like mpv_sponsorblock, install a folder

Signed-off-by: Nicola Smaniotto <smaniotto.nicola@gmail.com>

eclass/mpv-plugin.eclass

@@ -113,7 +113,7 @@ mpv-plugin_src_install() {
 	insinto "${MPV_INSTALL_DIR}"
 
 	for f in "${MPV_PLUGIN_FILES[@]}"; do
-		doins "${f}"
+		doins -r "${f}"
 	done
 
 	use autoload && if _mpv-plugin_has_main; then