Reacting to build errors from a Portfile (e.g. giving specific hints)

[René J. V. Bertin]

After actually reading the `trace` documentation I got a callback to work via 
that mechanism, but it's clearly not the way to go. There are of course way too 
many return statements between the entry of a given port phase and its 
potential 
bailing.

It looks like the best way to achieve what I'm looking for is to roll a custom 
`build {}` block that `catch`es errors in the actual build execution and might 
then even try to take the suggested corrective action and re-launch the build 
command.