Factor out replacement of calls to bodyless functions into separate pass

[peterschrammel]

...to enable custom replacements (assume(false), return nondet, full nondet sideeffects and returns, summaries, etc).

[tautschnig]

Note that there already is "undefined-function-is-assume-false" in goto-instrument. While I do agree that some factoring-out would be good, there is a risk of introducing even more command-line options to control the behaviour. I would strongly suggest that any such pass is done via goto-instrument.

[TGWDB]

Closing as a feature we're not actively working on (and have not been considering for a long time). Please reopen if you believe this is erroneous.