Clang now includes concepts in the mangled names of C++ functions: 4b163e343c
This adjusts the test to verify that we don't transitively emit the symbols referenced from the requires expression. Those symbols shouldn't be emitted because they are not executed.
rdar://127263407
Clang implicitly enables local submodule visibility when compiling in C++20 mode. ClangImporter does not support it, so let's disable it explicitly.
rdar://108959307 / https://github.com/apple/swift/issues/65710
