[xml] xsltSetTransformErrorFunc doesn't work

["Eric Haszlakiewicz" <EHASZLA transunion com>]

Specifically, it doesn't redirect output from things such as xsl:message
element
within a stylesheet.
Looking briefly at the code, it's fairly obvious why this happens:
xsltMessage(),
which is called when an xsl:message element is encountered, calls
xsltGenericError()
instead of xsltTransformError().
There are various other places that use xsltGenericError(), even though
they have a
xsltTransformContext and could call the transform error function.  So,
should all of
these places use xsltTransformError()?  I think that they should, so
transform error
function is actually useful.

eric