[tex4ht] xmllint calls, so many

[Karl Berry]

There are tons of calls to xmllint on every individual file.
It is annoying (and slow) to get those hundreds of lines of output that
everything's ok every time.

1) I wonder if we really care. But I guess it is good to check that
what's generated is valid.

2) In which case, I wonder if there is any feasible way to combine calls
to reduce the number of invocations and amount of output. xmllint
supposedly takes more than one file.

Unfortunately from a quick look it is invoked from tex4ht.env[-unix] and
it is only set up to do one file. Michal, have you roamed around in this
area at all? Any ideas? --thanks, karl.