Proposed autoconf change: rip out search for 'install'

I just got a note from Chris Williams to the effect that when he built
6.4 on his HPUX setup, the install step failed.  Seems that HP has
a largely incompatible program called "install" living in /etc, and
configure tried to use it.  (I hadn't ever noticed this because I don't
run with /etc in my path except when I'm root.  HP does offer a
compatible flavor of install in /opt/imake/bin...)

This brings up something I've been thinking for a while, but hadn't
gotten around to proposing.  I have noticed that most other large
packages that need "install" use an install script distributed
with the package; they all say there's too much variation in
vendor-supplied install programs to risk depending on those.
I say it's time we do the same.  We do already include an install script
(src/install-sh), so it's not at all clear what the value is of trying
to use a locally provided install program.  We're not saving space, and
we're wasting time during configure.

I propose taking out configure's search for an install program and
just letting it select install-sh always.  Anyone who really wanted
to use their local install could still override that decision by
changing Makefile.global.

Another alternative is to use the standard autoconf AC_PROG_INSTALL
macro, which contains some grotty tests to weed out incompatible
versions of install.  But I don't really see the reason for taking any
risk.

Comments?  Objections?
        regards, tom lane