Stop importing CF as a framework

Frameworks don't exist off of Darwin resulting in link failures in this
test. The CF modulemap declares CF as a framework everywhere, which is
wrong, but importing CF from swift-corelibs-foundation is also equally
wrong, which this test does as well, so there's a lot of wrongness.

To get the rebranch working, we need to stop importing CoreFoundation as
a framework in this test, or disable the test on non-darwin platforms.
Given that corelibs-xctest is for non-Darwin platforms, that seems like
the wrong course of action.

Author: etcwilde

Tests/Functional/Asynchronous/Expectations/main.swift

@@ -1,4 +1,4 @@
-// RUN: %{swiftc} %s -o %T/Asynchronous
+// RUN: %{swiftc} -Xfrontend -disable-autolink-framework -Xfrontend CoreFoundation %s -o %T/Asynchronous
 // RUN: %T/Asynchronous > %t || true
 // RUN: %{xctest_checker} %t %s