A serious problem in the design of qdoc is its
C++ parser. It is an ad hoc recursive descent
parser, which has not kept pace with Qt's use
of the more esoteric aspects of C++. Part of
the problem is that qdoc does not send files
through the preprocessor before processing
them. The bottom line is qdoc needs the C++
parser used in Qt Creator.

But that is a long-term solution. In the short
term, we have to introduce minor hacks like
this one to keep qdoc going until the parser
can be replaced.

The problem in this case is that qdoc doesn't
handle the QT_PREPEND_NAMESPACE macro in
function declarations. The solution is to let
qdoc ignore the macro and just use the macro's
parameter, which is what qdoc wants anyway.

Task-number: QTBUG-28953
Change-Id: I5b9efcc10fa8fb500a44854ee995c2e50e9e16b5
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>