[Bridging PCH] Add testcase for emitting, importing a bridging PCH file.

Author: graydon

test/ClangImporter/pch-bridging-header.swift

@@ -0,0 +1,11 @@
+// RUN: rm -rf %t && mkdir -p %t
+// RUN: %target-swift-frontend -emit-pch -o %t/sdk-bridging-header.pch %S/Inputs/sdk-bridging-header.h
+// RUN: %target-swift-frontend -parse -verify %s -import-objc-header %t/sdk-bridging-header.pch
+// REQUIRES: objc_interop
+
+import Foundation
+
+let not = MyPredicate.not()
+let and = MyPredicate.and([])
+let or = MyPredicate.or([not, and])
+