[clang] [llvm] Finish deleting the le32/le64 targets (PR #98497)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

> I was under the impression those bits were still needed for Chromium. CC @dschuff

Oh, clang/lib/CodeGen/Targets/PNaCl.cpp is still live for mipsel-nacl target triple.  Which we also have zero tests for, but I guess that's a separate issue.

https://github.com/llvm/llvm-project/pull/98497