Merge branch 'print_qt5_version' into 'release-6.6'

DOC: allow the configure step to print detected Qt5 version

See merge request orfeotoolbox/otb!76

Modules/ThirdParty/Qt/otb-module-init.cmake

@@ -24,3 +24,5 @@ find_package(Qt5Widgets REQUIRED)
 find_package(Qt5OpenGL REQUIRED)
 find_package(Qt5LinguistTools)
 mark_as_advanced( QT_QMAKE_EXECUTABLE )
+
+set(QT_VERSION_STRING ${Qt5Core_VERSION})