blacklist gcc version 4.0.0 on OSX

[sagetrac-mabshoff]

Any gcc 4.0.0 provided by Apple is buggier than a Florida swamp. Refuse to build Sage with it at start up!

Cheers,

Michael

Component: build

Issue created by migration from https://trac.sagemath.org/ticket/3114

[wjp]

comment:2

prereq currently checks for gcc >= 4.0.1, so this has already been taken care of.