QChar(char) constructor is private but is documented as if public

It hasn't ever been a public constructor in Qt 5 AFAIK. In qchar.cpp

/*!
\fn QChar::QChar(char ch)

Constructs a QChar corresponding to ASCII/Latin-1 character \a ch.
*/

same thing with the one taking a uchar. This needs auditing to see what else is documented incorrectly. Not sure if we should silently remove the docs or what...