manual: Convert @tables of annotated @items to @vtables.

manual: Convert @tables of annotated @items to @vtables.

The conversion script will convert these annotations, but the
replacement Summary-generation script won't catch them because @items
in @tables are not generally considered annotatable, causing them to
be skipped over (or cause errors).  Using @vtable ensures their
continued presence in the Summary, with the added benefit that Texinfo
will also automatically include them in the Variable and Constant
Macro index now.

	* manual/conf.texi: Convert @tables of annotated @items to
	@vtables.
	* manual/lang.texi: Likewise.
	* manual/pattern.texi: Likewise.
	* manual/resource.texi: Likewise.
	* manual/socket.texi: Likewise.