tie proxy factory support in SIP bindings to PyQt4 version instead of Qt

git-svn-id: http://svn.osgeo.org/qgis/trunk@13468 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: jef

python/CMakeLists.txt

@@ -35,10 +35,9 @@ IF(MSVC)
   ADD_DEFINITIONS(-DNOMINMAX)
 ENDIF(MSVC)
 
-MATH(EXPR QT_VERSION "${QT_VERSION_MAJOR}*10000 + ${QT_VERSION_MINOR}*100")
-IF(QT_VERSION LESS 40500)
+IF(${PYQT4_VERSION_STR} VERSION_LESS "4.6.0")
   SET(SIP_DISABLE_FEATURES ${SIP_DISABLE_FEATURES} PROXY_FACTORY)
-ENDIF(QT_VERSION LESS 40500)
+ENDIF(${PYQT4_VERSION_STR} VERSION_LESS "4.6.0")
 
 # core module
 FILE(GLOB sip_files_core core/*.sip)