Revert "[libc++] Remove workaround which allows setting _LIBCPP_OVERRIDABLE_FUNC_VIS externally (#113139)" (#117779)

This reverts commit 2e686d6d17c4cc7608510a856055e6ca79fcb917.

See https://github.com/llvm/llvm-project/issues/117571

GitOrigin-RevId: a94cec521202b00d18eaa55d9a5a4616097f5abf
1 file changed