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

[Glenn Morris]

Eli Zaretskii wrote:

>> That fixes the problem on GNU/Linux.
>
> How and why does it do that?  And what problem is that?

The problem that I reported with the argument names being lost (replaced
by ARG1 etc).

Because help-function-arglist calls help-split-fundoc which expects to
find \n\n(fn in the doc of built-in functions. It doesn't expect
functions to be built-in on some platforms and not on others.

Example:

--- pc-win.el   2012-02-11 19:22:20.968856000 -0800
+++ pc-win.el.~1~          2012-02-11 19:21:36.185359943 -0800
@@ -289,7 +289,9 @@
 FRAME should be a frame that should own the selection.  If omitted or
 nil, it defaults to the selected frame.
 
-On Nextstep, FRAME is unused."
+On Nextstep, FRAME is unused.
+
+\(fn SELECTION VALUE &optional FRAME)"
   (ignore-errors
     (x-select-text value))
   value)