[lltx] Can luatex auto-run mkluatexfontdb ?

[Karl Berry]

    > osx:
    > /System/Library/Fonts//;/Network/Library/Fonts//;/Library/Fonts//

      You probably also want $HOME/Library/Fonts// there.

I am not enthused about embedding system directories in our texmf.cnf,
which will inevitably change without warning with os releases, cause
weird problems/slowdowns for some users because their setups aren't the
same as yours, etc.

OSFONTDIR is there because Hans wanted it, that's the only reason.  I
guess some part of context setup/invocation sets it.  I think any
determination of the value should be done by some os-specific tool (that
TL does not maintain), not just a random hardwired list.

Maybe whatever context does can be extracted into a more general tool.
I dunno.  All I know is, I don't want to go there for the generic TL
release.  Sorry.