Meta attributes types are now enforce as of commit
90b9719f4fc95e54400a66bffcc8044c568cfa4b,
so ensure meta.priority is always set to an integer.
This fixes evaluation of `linuxPackages_latest.virtualbox`
(the impetus for this commit)
and other packages that use lowPrio or hiPrio.
I.e. append a suffix *before* the version, rather than after. So we
get "sqlite-interactive-3.8.0.2" instead of
"sqlite-3.8.0.2-interactive". The latter is broken since nix-env just
sees it the suffix as part of the version, so "nix-env -u" will
happily upgrade "sqlite-3.8.0.2-interactive" to "sqlite-3.9".
Nix-env always wants to install all outputs of a derivation, but this
failed for openjdk/openjre because openjdk has some symlinks (such as
bin/java) to openjre. Also, it prevents installing the openjre
without the openjdk. So as a workaround, mess with the "outputs"
attribute to fool nix-env.
Also, give openjre a separate name and description.
Fixes#1535.
