[xml] Header taint

["Igor Zlatkovic" <igor zlatkovic com>]

Hi there,

As promised, here it is. The headers have been tainted to contain export
declarations on every function, every variable.

New files called xmlexports.h, xsltexports.h and exsltexports.h contain the
macro definitions. Macros are:

  xPUBFUN for declaring public functions
  xPUBVAR for declaring public variables
  xCALL for stating the function calling convenction

where 'x' is XML, XSLT or EXSLT respectively. The default export defs are:

  #define XMLPUBFUN
  #define XMLPUBVAR extern
  #define XMLCALL

for libxml, analogue for libxslt and libexslt. This matches what has been
used so far on Unix, where everything should compile just the way it did
before.

What remains to be done is to align the parameters the way they were before
the taint. I'll do this. Libxml headers up to parser.h, alphabetically, have
been aligned allready. If someone wants to help, welcome :-), but let me
know what you are doing so we don't end up doing it twice.

This does not interferre with the .def file in any way. Makefiles are not
using the .def file anymore, but even if they would, things would go fine.
MS linker seems to accept both at the same time and they do not have to
match. It will export a symbol if it is either declared as exportable or
mentioned in the .def file, or both.

Please risk a glance at this and if there is a slightest problem, I'll
appreciate an email, a phone call in the middle of the night, whatever, but
this must work for the next release. Not only for the next release, it must
work before that. Before any additional change is made to the headers. This
must be, so the change so big as this one can be easily reverted if it
doesn't work.

Ciao,
Igor