Use X11/Xlib.h for checking where X11 can be found in stead of X11/XIntrinsic.h. Suggested by Pietro Cerutti. 
(Backported from tclconfig)
Use X11/Xlib.h for checking where X11 can be found in stead of X11/XIntrinsic.h. Suggested by Pietro Cerutti. 
(backported from tclconfig)