If a find_package() in a try_compile project doesn't find a package,
and we then link against a non-existent target, the configuration
failure of the compile test also fails the configuration of the
project.
To avoid that, separate library targets from non-targets, and make sure
to only link against the targets if they exist.
pro2cmake now outputs modified compile test project code which iterates
over targets and non-target libraries, and links against them when
needed.
Change-Id: Ib0f4b5f07af13929c42d01a661df2cabdf9b926b
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
066e8a4557