Accumulating PPC_FEATURE_ARCH bits

If one wants to test the PPC_FEATURE_ARCH_ISA_2_0[56] bits, one has to be careful that if 2_06 is set, 2_05 won't be. This seems illogical to me: given that 2.06 includes all of the 2.05 instructions, it would make most sense if both bits were set in the hwcap.

Now, obviously I have to code around existing practice, but going forward this isn't tennable. When a Power 2.07 ISA is released, I'd rather not have existing programs degrade because suddenly the 2_06 bit is no longer set.

Thanks,

r~