Detect native tqt3 in a reliable manner

This closes Bug 816

ConfigureChecks.cmake

@@ -50,7 +50,6 @@ if( NOT DEFINED QT_INCLUDE_DIR )
   if( QT_PREFIX_DIR STREQUAL "/usr" )
     if( EXISTS "${QT_PREFIX_DIR}/include/tqt${QT_VERSION}" )
       set( QT_INCLUDE_DIR "${QT_PREFIX_DIR}/include/tqt${QT_VERSION}" )
-      set( HAVE_REAL_TQT ON CACHE BOOL "Native TQt3 detected" )
     else( )
       set( QT_INCLUDE_DIR "${QT_PREFIX_DIR}/include/qt${QT_VERSION}" )
     endif( )
@@ -60,6 +59,13 @@ if( NOT DEFINED QT_INCLUDE_DIR )
 endif( )
 qt_message( "  QT_INCLUDE_DIR: ${QT_INCLUDE_DIR}" )
 
+# detect native tqt
+if( EXISTS "${QT_INCLUDE_DIR}/ntqglobal.h" )
+  set( HAVE_REAL_TQT ON CACHE BOOL "Native TQt3 detected" )
+  qt_message( "Native TQt3 detected" )
+else( )
+  qt_message( "Qt3 detected" )
+endif( )
 
 # qt library path
 if( NOT DEFINED QT_LIBRARY_DIR )