fail() causes compiler to exit

[Martin Sjölund]

Using dynamic loading of functions that fail() causes the compiler to exit with a thrown exception. This should be caught. However, Ceval also must not call the function again, so a result Values.META_FAIL() should be returned. This is necessary for future optimizations (and interpretation/ceval of matchcontinue expressions), and for providing good error messages if a constant is bound to a call that fail()'ed.

{{{function func

input Integer i;
output Integer b;

algorithm

b := match (i)

case (_) then fail();

end match;

end func;}}}