[clang] [OpenMP] Don't emit redundant zero-sized mapping nodes for overlapped structs (PR #148947)

[Qinkun Bao via cfe-commits]

qinkunbao wrote:

Hi, this PR broke a few buildbots? Could you please take a look? e.g.,
https://lab.llvm.org/buildbot/#/builders/66/builds/16945

https://github.com/llvm/llvm-project/pull/148947