[clang] [WIP][clang] Fix std::tm etc. mangling on Solaris (PR #106353)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

> just leads to infinite recursion (obviously),

Try casting the pointer to uintptr_t?

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Might be simpler to mess with CXXNameMangler::mangleUnscopedName, though, which I think is where the St prefix is getting added.

https://github.com/llvm/llvm-project/pull/106353