[sourcekitd] Add test case for rdar://70017224

rdar://70017224 seems to be fixed. Add a test case for it.

Author: ahoppen

test/SourceKit/CursorInfo/rdar_70017224.swift

@@ -0,0 +1,15 @@
+// RUN: %empty-directory(%t)
+
+// RUN: echo '@_typeEraser(AnyView) public protocol View {}' > %t/Module.swift
+// RUN: echo 'public struct AnyView : View {' >> %t/Module.swift
+// RUN: echo ' public init<T: View>(erasing: T) {}' >> %t/Module.swift
+// RUN: echo '}' >> %t/Module.swift
+// RUN: %swift -emit-module -o %t/Module.swiftmodule %t/Module.swift -parse-as-library
+
+// RUN: %sourcekitd-test -req=cursor -pos=13:13 %s -- -I %t %s | %FileCheck %s
+
+import Module
+
+struct Foo: View {}
+
+// CHECK: <Declaration>@_typeEraser(<Type usr="s:6Module7AnyViewV">AnyView</Type>) protocol View</Declaration>