Write qtversion to pkg config file.

CMakeLists.txt

@@ -73,12 +73,14 @@ IF(NOT CLIENT_ONLY)
     FIND_PACKAGE(PythonQt COMPONENTS QtAll)
     SET(GEPETTO_GUI_HAS_PYTHONQT (${PythonQt_FOUND} AND ${PythonQt_QtAll_FOUND}) CACHE BOOL "Use PythonQt dependency")
     ADD_DEFINITIONS(-DUSE_QT4)
+    SET(PKG_CONFIG_EXTRA "qtversion: ${QT_VERSION_MAJOR}.${QT_VERSION_MINOR}.${QT_VERSION_PATCH}")
   ELSE(USE_QT4)
     FOREACH (component "Core" "Widgets" "Gui" "OpenGL" "Network")
       FIND_PACKAGE ("Qt5${component}" REQUIRED)
       LIST(APPEND QT_INCLUDE_DIRS ${Qt5${component}_INCLUDE_DIRS})
       LIST(APPEND QT_LIBRARIES    ${Qt5${component}_LIBRARIES}   )
     ENDFOREACH (component "Core" "Widgets" "Gui" "OpenGL" "Network")
+    SET(PKG_CONFIG_EXTRA "qtversion=${Qt5Core_VERSION}")
   ENDIF(USE_QT4)
 
   PKG_CONFIG_APPEND_LIBS(${PROJECT_NAME})