Print summary of failed modules when there is a build failure

Currently when there is a build failure, the bottom of the build output looks like this:

[00:02:10] FAILURE Build failed



Pipeline Summary
  Total:       214
  Session:     12
  Pull Queue:  processed 0, skipped 12, failed 0 
  Fetch Queue: processed 0, skipped 12, failed 0 
  Build Queue: processed 4, skipped 0,  failed 2 

It tells me how many modules failed, which is nice, but it'd be better to show at a glance which modules failed.

added Enhancement Frontend labels

mentioned in issue #252 (closed)

This is very similar to #252 (closed) - and should probably be worked on together.

added Logging and removed Frontend labels

Besides printing the name of the failed elements, I suggest that we also print either an identifier or the path to the corresponding log file. And the same for the failed build tree. That way you can build a large number of components with --on-error continue and can still view logs of all failed elements and even enter the failed build trees using bst shell --sysroot.

changed milestone to %Immediate Priorities

mentioned in merge request !329 (merged)

closed via merge request !329 (merged)