Add EXACT to the rule for adi 8, in the same way that the old rules
for and 8, ior 8, xor 8 have EXACT.
Add rules for sli 8 and sru 8 when shifting 32 bits, and add
assertions in llshift_e.c to test these rules.
Add tests for comparisons and shifts. Also add enough integer
conversions to compile the shift test (llshift_e.c), and disable
some wrong rules for ldc and conversions.