[XLA] Add parser and codegen for more CPU architectures
I modified the patch slightly to make inclusion of targets conditional on the bazil configuration. Please reopen if this does not fix your issue. Thank you for letting me know. I will reopen it if it does not work.
This PR adds parser and codegen for PowerPC and SystemZ to execution engine in XLA runtime.

I saw the following error w/o this PR when I ran Jax on s390x
```
$ python tests/core_test.py 
Traceback (most recent call last):
  File "/home/ishizaki/Jax/jax/tests/core_test.py", line 26, in <module>
    import jax
  File "/home/ishizaki/Jax/jax/jax/__init__.py", line 35, in <module>
    from jax import config as _config_module
  File "/home/ishizaki/Jax/jax/jax/config.py", line 17, in <module>
    from jax._src.config import config  # noqa: F401
  File "/home/ishizaki/Jax/jax/jax/_src/config.py", line 28, in <module>
    from jax._src import lib
  File "/home/ishizaki/Jax/jax/jax/_src/lib/__init__.py", line 87, in <module>
    import jaxlib.xla_client as xla_client
  File "/home/ishizaki/Jax/.venv/lib/python3.10/site-packages/jaxlib/xla_client.py", line 26, in <module>
    from . import xla_extension as _xla
ImportError: /home/ishizaki/Jax/.venv/lib/python3.10/site-packages/jaxlib/xla_extension.so: undefined symbol: LLVMInitializeSystemZAsmParser
```