Partac: don't drop critical exceptions
Partac: don't drop critical exceptions

Not sure why exactly, but without this change raising a critical
exception (eg anomaly, assert false) in a par: tactic gets ignored.

coq/coq,SkySkimmer/coq,SkySkimmer/coq,coq/coq,coq/coq,SkySkimmer/coq,SkySkimmer/coq,ejgallego/coq,coq/coq,ejgallego/coq,ejgallego/coq,ejgallego/coq