### Implement set[n]bc[r] instructions

```This implements the setbc, setnbc, setbcr and setnbcr instructions.
Because the insn_type_t type already has 64 elements, this uses the
existing OP_SETB for the new instructions, and has execute1 compute
different results depending on bits 6-9 of the instruction.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>```
 `@ -836,14 +836,27 @@ begin` ` end if;` ` misc_result <= mfcr_result;` ` when "110" =>` ` -- setb` ` bfa := insn_bfa(e_in.insn);` ` crbit := to_integer(unsigned(bfa)) * 4;` ` -- setb and set[n]bc[r]` ` setb_result := (others => '0');` ` if cr_in(31 - crbit) = '1' then` ` setb_result := (others => '1');` ` elsif cr_in(30 - crbit) = '1' then` ` setb_result(0) := '1';` ` if e_in.insn(9) = '0' then` ` -- setb` ` bfa := insn_bfa(e_in.insn);` ` crbit := to_integer(unsigned(bfa)) * 4;` ` if cr_in(31 - crbit) = '1' then` ` setb_result := (others => '1');` ` elsif cr_in(30 - crbit) = '1' then` ` setb_result(0) := '1';` ` end if;` ` else` ` -- set[n]bc[r]` ` crbit := to_integer(unsigned(insn_bi(e_in.insn)));` ` if (cr_in(31 - crbit) xor e_in.insn(6)) = '1' then` ` if e_in.insn(7) = '0' then` ` setb_result(0) := '1';` ` else` ` setb_result := (others => '1');` ` end if;` ` end if;` ` end if;` ` misc_result <= setb_result;` ` when others =>`
 `@ -336,6 +336,10 @@ architecture behaviour of predecoder is` ` 2#0_00101_11010# => INSN_prtyd,` ` 2#0_00100_11010# => INSN_prtyw,` ` 2#0_00100_00000# => INSN_setb,` ` 2#0_01100_00000# => INSN_setb, -- setbc` ` 2#0_01101_00000# => INSN_setb, -- setbcr` ` 2#0_01110_00000# => INSN_setb, -- setnbc` ` 2#0_01111_00000# => INSN_setb, -- setnbcr` ` 2#0_01111_10010# => INSN_slbia,` ` 2#0_00000_11011# => INSN_sld,` ` 2#0_00000_11000# => INSN_slw,`