x11/cde*: Work around bus errors and looping CDE apps

-O2 optimization is too aggressive for CDE. Scaling it back to -O
eliminates bus errors on some systems and dtcalc looping with the
error, *** M .LE. T IN CALL TO MPCHK.

Reported by: Jeremy Doolin <jrdoolin@pm.me>
MFH: 2026Q2