[clang] [CIR][RISCV] Support zbc builitin codegen (PR #193685)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ppc64le-flang-rhel-clang` running on `ppc64le-flang-rhel-test` while building `clang` at step 6 "test-build-unified-tree-check-flang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/157/builds/46346

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-flang) failure: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
...
PASS: Flang :: Driver/mcmodel.f90 (4426 of 4436)
PASS: Flang :: Driver/options-loongarch.f90 (4427 of 4436)
PASS: Flang :: Transforms/debug-omp-target-op-1.fir (4428 of 4436)
PASS: Flang :: Transforms/vscale-attr.fir (4429 of 4436)
PASS: Flang :: Driver/use-module-error.f90 (4430 of 4436)
PASS: Flang :: Transforms/debug-line-table.fir (4431 of 4436)
PASS: Flang :: Driver/fopenmp.f90 (4432 of 4436)
PASS: Flang :: Lower/OpenMP/rtl-flags.f90 (4433 of 4436)
PASS: Flang :: Driver/omp-driver-offload.f90 (4434 of 4436)
PASS: Flang :: Driver/linker-options.f90 (4435 of 4436)
command timed out: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=3611.489244

```

</details>

https://github.com/llvm/llvm-project/pull/193685