[xslt] Link error if libxml2 is compiled without HTML support

[Jesse Pelton <jsp PKC com>]

Caveat: I may have messed something up, because I'm using our in-house build
system rather than the provided makefiles.

I'm running Windows 2000. Here's the problem: if I build libxml2 without
HTML support (cscript configure.js html=no), then build libxslt, then link a
program, I get four unresolved externals:
- htmlDocContentDumpOutput, htmlDocContentDumpFormatOutput, and
htmlSetMetaEncoding referenced in xsltSaveResultTo
- htmlNewDoc referenced in xsltDocumentElem

I'm not sure whether this is intended (that is, libxslt requires HTML
support in libxml2) or not. I *think* libxslt could be patched to respect
LIBXML_HTML_ENABLED.  (It already respects LIBXML_DOCB_ENABLED, though that
appears a little easier.)

Also, "output" is misspelled as "ouput" in xsltutils.c and numbers.c.