libxml2: wrap xmllint to use the correct XML catalogues
Install a wrapper around xmllint in native builds to set
XML_CATALOG_FILES to the correct location of the XML catalogues, so that
the callers of this script (like xmlto) don't need to do the same.
Signed-off-by: Ross Burton <ross.burton@arm.com> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>