The name __deref is defined as a macro by Windows headers.
This renames the __deref() helper function to __ref. It doesn't actually
dereference an iterator. it just has the same type as the iterator's
reference type.
libstdc++-v3/ChangeLog:
PR libstdc++/97362
* doc/html/manual/source_code_style.html: Regenerate.
* doc/xml/manual/appendix_contributing.xml: Add __deref to
BADNAMES.
* include/debug/functions.h (_Irreflexive_checker::__deref):
Rename to __ref.
* testsuite/17_intro/badnames.cc: Check __deref.
