[Bug target/106600] New: __builtin_bswap32 is not hooked up for ZBB

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106600

            Bug ID: 106600
           Summary: __builtin_bswap32 is not hooked up for ZBB
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: target
          Assignee: pinskia at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---
            Target: riscv32

Testcase:
```
int f(int a)
{
  return __builtin_bswap32(a);
}
```
The reason is because the check for TARGET_64BIT is there even though it should
not be:
(define_insn "bswap<mode>2"
  [(set (match_operand:X 0 "register_operand" "=r")
        (bswap:X (match_operand:X 1 "register_operand" "r")))]
  "TARGET_64BIT && TARGET_ZBB"
  "rev8\t%0,%1"
  [(set_attr "type" "bitmanip")])