[Development] OS X plugin naming bug

[Hanspeter Niederstrasser]

On OS X, Qt is building plugins as dynamic libraries, instead of 
bundles, which is the more appropriate format for the platform. This was 
filed as QTBUG 2227 six years ago, but it was marked as closed without 
any work done on it, even though there was a patch listed.  For the Fink 
package manager, we have been successful in locally patching the Qt4 and 
Qt5 sources to correct the plugin file type and extension.

However, when I tried to start building the KDE5 frameworks on OS X, a 
new related issue appeared whereas the Qt5 cmake files referenced the 
plugin with the original .dylib extension and not the patched .so 
extension that the physical file is now using (this is all documented in 
QTBUG 2227). I have not been able to find the code that generates the 
.cmake files to figure out why it is not honoring the file extension 
change. It was suggested on IRC that I reach out to the qt-dev mailing 
list to get a fresh look at QTBUG 2227. Thank you for your help,

Hanspeter