Type compatibility problem with ?:

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=3412

Reported by Martin Nilsson, IDA nilsson@pike.ida.liu.se

It is possible to run 1?throw(1):1; in Pike up until 7.2. Then in Pike 7.4
it produces the error "The arguments to ?: may not be void." IMO the above
expression should be allowed in Pike 7.4 as well. In any case it needs
compatibility junk if the yyerror is to remain.