'make <package>' shouldn't always say "Sage build/upgrade complete!"

[nexttime]

If for example a full build of Sage got interrupted or failed, and one afterwards does

make some_package

and the latter succeeded, one at the end gets

Sage build/upgrade complete!

even though Sage isn't yet fully built.

(This message comes from build/make/install, a shell script called from the top-level Makefile, which in turn invokes make on build/make/Makefile.)

---

We could check $1 also before printing that message, and/or add

if $MAKE -q "$target" >/dev/null 2>/dev/null; then
    # $target is up-to-date 
    ...
else
    # $target hasn't fully been built yet
    ...
fi

there again (with target=all or probably =all-build).

Also, the hint on installing scripts should now be given if $1 = all-build as well.
(We could perhaps move it into the Makefile / deps anyway.)

CC: @jdemeyer

Component: build

Issue created by migration from https://trac.sagemath.org/ticket/21134

[nexttime]

comment:1

Even after just downloading an upstream package tarball (./sage -i -d <package>), Sage afterwards says "Sage build/upgrade complete", which is simply plain wrong and misleading.