libvorbis: Update to version 1.3.7

libvorbis: Update to version 1.3.7

- Update from version 1.3.6 to 1.3.7
- Update of rootfile
- Changelog
   libvorbis 1.3.7 (2020-07-04)
	* Fix CVE-2018-10393 - out-of-bounds read encoding very low sample rates.
	* Fix CVE-2017-14160 - out-of-bounds read encoding very low sample rates.
	* Fix handling invalid bytes per sample arguments.
	* Fix handling invalid channel count arguments.
	* Fix invalid free on seek failure.
	* Fix negative shift reading blocksize.
	* Fix accepting unreasonable float32 values.
	* Fix tag comparison depending on locale.
	* Fix unnecessarily linking libm.
	* Fix memory leak in test_sharedbook.
	* Update Visual Studio projects for ogg library filename change.
	* Distribute CMake build files with the source package.
	* Remove unnecessary configure --target switch.
	* Add gitlab CI support.
	* Add OSS-Fuzz support.
	* Build system and integration updates.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Reviewed-by: Peter Müller <peter.mueller@ipfire.org>