Fix ECMCheckOutboundLicenseTest to find the FindReuseTool.cmake file

Not sure if this only broke with some more recent cmake version, the related ECM configure warnings only caught my awareness recently. But at least when using cmake 3.19.5 the test was missing out to find the FindReuseTool.cmake file since the test was introduced. Good news is that the test passes still when actually triggered :)

Separate commit removes some noise from the configuration log: similar configure-time generation is not chatty about what it generates (think export or forward headers etc), so this info seems out-of-place, also is information which usually is uninteresting when running cmake.

@cordlandwehr @adridg @cgiboudeaux