[clang] [llvm] [MC/DC][Coverage] Loosen the limit of NumConds from 6 (PR #82448)

[NAKAMURA Takumi via cfe-commits]

chapuni wrote:

For now, I've implemented almost functionalities for this.

Both `-fmcdc-max-conditions=32767` and `-fmcdc-max-test-vectors=0x7FFFFFFE` are cc1options.

`llvm-cov` can understand `clang-18`'s profdata (and objects).

TODO: documents and test cases

https://github.com/llvm/llvm-project/pull/82448