Revert "Revert "Fix def_exc"" -- forgot to undo revert, wait for #83.
Revert "Revert "Fix def_exc"" -- forgot to undo revert, wait for #83.

This reverts commit 99883f7df25761db1638cb115e3df236bdad2d27.

goblint/analyzer,goblint/analyzer,goblint/analyzer,goblint/analyzer,goblint/analyzer