Strong constraints on make install

[Akim Demaille]

The GCS require that "make install" does not use

        install FILES... DIR

That's in make-stds:

> @noindent
> Always use a file name, not a directory name, as the second argument  
> of
> the installation commands.  Use a separate command for each file to be
> installed.

I suppose, but I'm not sure, that this is in order to let some
tools postprocess the logs of a "make install".

But that constraints result in bazillions of "install" invocations.
Jim Meyering reported privately that Gettext's "make install"
results in 1200 "install" invocations!!!

That's very expensive, and it can be considerably improved if
the GCS were relaxed on this regard.  There is no portability
issue: install-sh already does the right thing, so the
matter is purely to comply with the standard.

Thanks!