Removed the forced setting of DLIB_NO_GUI_SUPPORT in the cmake file

since it is sort of irritating.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402568

dlib/CMakeLists.txt

@@ -144,7 +144,6 @@ INCLUDE(TestForANSIStreamHeaders)
 
 
 if (DLIB_ISO_CPP_ONLY)
-   set(DLIB_NO_GUI_SUPPORT ON CACHE STRING ${DLIB_NO_GUI_SUPPORT_STR} FORCE )
    add_global_define(DLIB_ISO_CPP_ONLY)
 else()
    remove_global_define(DLIB_ISO_CPP_ONLY)