Command line arguments, configure tests and features are now
defined in a json file and a configure.pri containing some
custom functions.
qmake uses the json file to determine command line arguments,
tests and features to be executed at configuration time.
A new qt_configure.prf contains all the infrastructure to parse
the command line, run the configure tests, determine the set of
available features and create a report about it.
Change-Id: If30ac089dd3e9f8c67ebd642bde10cfa960893bb
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>