Deployment issue on OSX with Qt 5.5

[Alexander Wolf]

Stellarium can't be deployment when Qt 5.5 are used for their building.

Typical log:

Scanning dependencies of target mac_app
making the macosx bundle.
Traceback (most recent call last):
  File "util/mac_app.py", line 276, in <module>
    main()
  File "util/mac_app.py", line 265, in main
    processFrameworks()
  File "util/mac_app.py", line 117, in processFrameworks
    copyFrameworkToApp(framework)
  File "util/mac_app.py", line 67, in copyFrameworkToApp
    shutil.copytree(frameworkRoot, target, symlinks=True, ignore=shutil.ignore_patterns('*debug*'))
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 168, in copytree
    names = os.listdir(src)
OSError: [Errno 2] No such file or directory: '@rpath/QtConcurrent.framework'
make[3]: *** [CMakeFiles/mac_app] Error 1
make[2]: *** [CMakeFiles/mac_app.dir/all] Error 2
make[1]: *** [CMakeFiles/mac_app.dir/rule] Error 2
make: *** [mac_app] Error 2