(selection-coding-system)

(selection-coding-system)
(next-selection-coding-system): Declaration moded from xselect.c.
(x-get-selection): Decode by selection-coding-system if it is
non-nil.  If it is nil, decode by a proper coding system.  Handle
C_STRING.
(ccl-check-utf-8, string-utf-8-p): Delete them.
(xselect-convert-to-string): Fix determining data-type in the case
that TEXT is requested.  Don't use selection-coding-system if it's
not proper for the data-type.