c++: Unneeded export query [PR 99380]

c++: Unneeded export query [PR 99380]

This problem got introduced fixing a module numbering problem.  When
preprocessing a header unit, we don't need to send an EXPORT query
unless we're also determining dependencies, or the mapper asked us
to.  Sadly the testsuite isn't set up to test this kind of subtlety.
I manually did that with stdin/stdout.

	PR c++/99380
	gcc/cp/
	* module.cc (name_pending_imports): Drop 'atend' parm.  Don't
	query export when not needed.
	(preprocess_module, preprocessed_module): Adjust.