[Swan-dev] replace "make check UPDATEONLY=1" with "make update"

[Andrew Cagney]

(more local hacks)

Paul mentioned I could update all the test VMs by, from the
testing/pluto directory, entering:

    make check UPDATE=1

and then hit cntrl-c a short while later.  Turns out, if you sacrifice
several chickens (try reading the code for why), you can get:

    make check UPDATEONLY=1

to just do the update.

I'd like to replace this with a simpler and more transparent "update"
target (or update-kvm or update-vm or update-test-vm or ...).  This
would mean:

old: make check
new: make check

old: make UPDATE=1 check
new: make update check
(that's two less characters to type)

old: make UPDATEONLY=1 check
new: make update
(that's 12 less characters to type!)

I could probably hold my nose and leave UPDATE=1 but not UPDATEONLY.

Andrew