The documentation of gfortran options uses @code wrappings for arguments
to @opindex.  This is superfluous, as 'op' index is a texinfo 'code' index,
that is it already implicitly formats its arguments as if in a @code block.
The superfluous wrapping has the effect of creating a nested
<code class="..."> tag inside the regular automatic <code> tag, in the
option index HTML page, preventing the recognition of the corresponding
option by the option URL generation script.

This change removes those superfluous @code wrappings.  Additionally,
variables appearing as separate argument in index are removed, permitting
a few more URL recognition.  Finally, the URL files are regenerated with the
new URLs recognized on the updated HTML files.

By the way, a spurious 'option' is removed from the label of the std= option
in the index, without any effect on URL recognition.

	PR other/116801

gcc/fortran/ChangeLog:

	* invoke.texi: Remove @code wrapping in arguments to @opindex.
	(std=): Remove spurious 'option' in index.
	(idirafter, imultilib, iprefix, isysroot, iquote, isystem,
	fintrinsic-modules-path): Remove variable from index.
	* lang.opt.urls: Regenerate.

gcc/ada/ChangeLog:

	* gcc-interface/lang.opt.urls: Regenerate.

gcc/c-family/ChangeLog:

	* c.opt.urls: Regenerate.

gcc/ChangeLog:

	* common.opt.urls: Regenerate.

gcc/d/ChangeLog:

	* lang.opt.urls: Regenerate.

gcc/go/ChangeLog:

	* lang.opt.urls: Regenerate.

gcc/m2/ChangeLog:

	* lang.opt.urls: Regenerate.

gcc/rust/ChangeLog:

	* lang.opt.urls: Regenerate.