[libcxx] [mlir] [flang] [llvm] [clang] [Flang][OpenMP] : Add a temporary lowering for workshare directive (PR #78268)

[Tom Eccles via cfe-commits]

tblah wrote:

This patch also needs to remove the TODO here https://github.com/llvm/llvm-project/blob/ef67f63fa5f950f4056b5783e92e137342805d74/flang/lib/Lower/OpenMP.cpp#L3550

https://github.com/llvm/llvm-project/pull/78268