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

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

It looks like the removal missed a few bits: PNaClABIBuiltinVaList and clang/lib/CodeGen/Targets/PNaCl.cpp weren't removed.

> Unfortunately, this utterly breaks Halide, which was in fact relying on both of these targets.

We can temporarily revert this, but we aren't going to leave the orphaned remains of PNaCl in-tree forever.  If you need a "halide" target long-term, please write up a proposal on Discourse describing exactly what bits you need, why you need them, relevant test coverage in-tree and out-of-tree, and a proposed code owner for those bits.

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