Don't export private include paths if there are no private includes

Needed when building Qt Creator with CMake + Qt6 non-prefix build.
Specifically qttools's QtUiPlugin does not have any private headers,
but the non-existing include path was exported, which caused an error
when configuring Qt Creator.

Change-Id: I662bc502fe3134fba083bde273b7f63fe1470277
Reviewed-by: Leander Beernaert <leander.beernaert@qt.io>
Reviewed-by: Qt CMake Build Bot
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

0 files changed, 0 insertions, 0 deletions