Order of docs for target options

[Joseph S. Myers]

The documentation in invoke.texi for target options doesn't seem to have
any particular logic to the order in which options for different machines
are listed; and this order differs in the summary list of options and in
the subsections for the individual machines.  I think there should be some
consistent and logical ordering; what should it be?  I'm inclined to make
it be alphabetical order of the directory name under "config" used for the
system; with options only applying to a specific operating system on a
specific machine going after those for that machine ("DEC Alpha/VMS
Options" is the only current example in the documentation), and those
applying to a specific operating system but on multiple machines going
after all those applying to specific machines ("System V Options" is the
only current example in the documentation).

-- 
Joseph S. Myers
jsm28@cam.ac.uk