bug#10783: Some built-in functionslost their argument names

[Glenn Morris]

Package: emacs
Version: 24.0.93

Current trunk on x86_64 GNU/Linux:

emacs -Q
C-h f x-get-selection-internal

  x-get-selection-internal is a built-in function in `xselect.c'.

  (x-get-selection-internal ARG1 ARG2 &optional ARG3 ARG4)


It has lost the argument names.
Actually, it is also missing the entire second paragraph of the doc
("TERMINAL should be a terminal object...").


In 23.4, it says:

  x-get-selection-internal is a built-in function in `C source code'.

  (x-get-selection-internal SELECTION-SYMBOL TARGET-TYPE &optional TIME-STAMP)


Similar problem for at least x-disown-selection-internal,
x-own-selection-internal. It still works for eg x-get-atom-name though.

`documentation' no longer returns the "(fn )" part, which causes
help-split-fundoc to return nil.