kerTeX: do update get_mk_install.rc to succeed

kerTeX: do update get_mk_install.rc to succeed

[tlaronde]

In the logs I see tries to install kerTeX on Plan9 but without hget'ing
first the last version of get_mk_install.rc.

But I have changed the name of the recipe for building the core (CM
compiled fonts and others; plain dumps). So the "old" script will work
by side effect because kertex.sh is still there; but if one updates
pkg/tools, the core and the script is removed.

Long explication: the pkg framework is file hierachy based. A pkg that
depends, say, on latex is under latex/. A "nickname" like
french@babel@tex will be put in tex/babel/french.

Since I use the pkg framework to compile the core fonts and the
core formats (plain METAFONT, plain TeX, plain e-TeX and plain
MetaPost) I had to give a name to the recipe. I called it "kertex"
but it was a bad idea:  what is "kertex"? The programs installed?
The package built? This was confusing. So I changed this. And in order
to have the same logics but not "pollute" the hierarchy with a spurious
"root" directory, it is now called tools@pkg.sh.

Other changes may happen in the future till the 1.0 release.

So when upgrading please do always retrieve the latest version of the
script since it is made to match the release.

Thanks!
-- 
        Thierry Laronde <tlaronde +AT+ polynum +dot+ com>
                     http://www.kergis.com/
                    http://kertex.kergis.com/
                       http://www.sbfa.fr/
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