DR considers the Q and GE flags to be arithmetic for saving, restoring, and in the EFLAGS_ARITH constant, yet not in the EFLAGS_{READ,WRITE}_ARITH defines. We correct that here by including them in all arithmetic defines.
Re-enables the drreg test that was broken because of this.
Relaxes a drreg assert on re-spilling to the aflags slot with different regs, which is exposed by this fix. This relaxation mirrors what we already do on restoring aflags.
Fixes #2360 (closed)