[flang] [llvm] [flang][OpenMP] Parse DOACROSS clause (PR #115396)

[Krzysztof Parzyszek via llvm-commits]

kparzysz wrote:

The code looked the same (except for the //) in the committed version, but when I ran clang-format on it, it reformatted this function.  If I added a commit that simply deleted the extra comment, the pre-commit clang-format would complain about formatting of this function, so I squashed/force-pushed the PR to make it look like this function wasn't modified at all.  Hopefully clang-format will leave it alone.

https://github.com/llvm/llvm-project/pull/115396