[libc-commits] [libc] [libc] Provide empty definitions for weak symbols (PR #173412)

[Roland McGrath via libc-commits]

frobtech wrote:

This is easy to approve for the `teardown_main_tls` symbol, but might require more discussion wrt `__cxa_thread_finalize`.  So let's make it two separate changes, and use the second one to more thoroughly discuss issues with the `__cxa_thread_finalize` symbol name / ABI in particular.

https://github.com/llvm/llvm-project/pull/173412