[clang] [Modules] Mark CFProtectionOptions.def as a textual header because it is used for x-macro purposes. (PR #110780)

[Volodymyr Sapsai via cfe-commits]

vsapsai wrote:

CI error
```
Traceback (most recent call last):
  File "/var/lib/buildkite-agent/builds/linux-56-59b8f5d88-r8xzr-1/llvm-project/github-pull-requests/libcxx/utils/generate_iwyu_mapping.py", line 92, in <module>
    main(sys.argv[1:])
  File "/var/lib/buildkite-agent/builds/linux-56-59b8f5d88-r8xzr-1/llvm-project/github-pull-requests/libcxx/utils/generate_iwyu_mapping.py", line 82, in main
    raise RuntimeError(f"{header}: Header {public} is not a valid header")
RuntimeError: __cxx03/__algorithm/adjacent_find.h: Header cxx03 is not a valid header
```
is unrelated to the current change.

https://github.com/llvm/llvm-project/pull/110780