libroxml: bump version to 2.3.0

Starting with version 2.3.0, libroxml is now using autotools.
With autotools, the -Werror flag was dropped
	-> no need for the patch libroxml-0001-werror.patch
With autotools, the availability of -Wno-*-unused is auto detected
	-> no need for the patch libroxml-0002-wno-unused-result.patch

Signed-off-by: Tristan Lelong <tristan.lelong@blunderer.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>