Added if () block to avoid script variables set to NOT-Found being used in searching

git-svn-id: http://svn.openscenegraph.org/osg/OpenSceneGraph/trunk@14624 16af8721-9629-0410-8352-f15c8da7e697

CMakeModules/FindGLIB.cmake

@@ -83,6 +83,8 @@ else()
     )
 endif()
 
+if (GLIBCONFIG_INCLUDE_DIR)
+
     set(GLIB_INCLUDE_DIRS ${GLIB_INCLUDE_DIR} ${GLIBCONFIG_INCLUDE_DIR})
 
     # Version detection
@@ -134,3 +136,7 @@ mark_as_advanced(
         GLIB_INCLUDE_DIRS
         GLIB_LIBRARIES
     )
+
+else()
+
+endif ()