Louis Dionne a55221da60 [clang] Revert changes to prefer the toolchain-provided libc++.dylib ...

This patch reverts the change that made clang prefer the toolchain
libc++.dylib when there is one (#170303), and the subsequent test
workaround we landed to fix bots (#170912).

We are seeing some failure on macOS LLDB bots that need to be
investigated, and that will require more time than I can spare
before the end of today.

This reverts commits bad1a88963 and 190b8d0b.

2025-12-05 16:45:41 -05:00

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usr

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