qmake: Avoid writing glue project file when only generating prl files

When qmake is run with -prl we don't need to write the glue makefile,
and doing so will end up with MakefileGenerator::writeProjectMakefile
trying to write to an invalid Option::output, resulting in warnings:

  QIODevice::write device not open

Change-Id: I196b185570e7329c621c2ccb8530b43f4be51ee6
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

0 files changed, 0 insertions, 0 deletions