Temporarily fix end-to-end remote mirror tests to OS X

There is an issue with writing to pipes under heavy load in the iOS
simulator but is intermittent. Disabling the tests there while I
investigate.

rdar://problem/26230879

Author: bitjammer

validation-test/Reflection/example.swift

@@ -3,6 +3,9 @@
 // RUN: %target-run %target-swift-reflection-test %t/example | FileCheck %s --check-prefix=CHECK-%target-ptrsize
 // REQUIRES: objc_interop
 
+// rdar://problem/26230879
+// REQUIRES: OS=macosx
+
 import SwiftReflectionTest
 
 class Container {

validation-test/Reflection/existentials.swift

@@ -3,6 +3,9 @@
 // RUN: %target-run %target-swift-reflection-test %t/existentials | FileCheck %s --check-prefix=CHECK-%target-ptrsize
 // REQUIRES: objc_interop
 
+// rdar://problem/26230879
+// REQUIRES: OS=macosx
+
 /*
    This file pokes at the swift_reflection_projectExistential API
    of the SwiftRemoteMirror library.

validation-test/Reflection/functions.swift

@@ -3,6 +3,9 @@
 // RUN: %target-run %target-swift-reflection-test %t/functions 2>&1 | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-%target-ptrsize
 // REQUIRES: objc_interop
 
+// rdar://problem/26230879
+// REQUIRES: OS=macosx
+
 /*
    This file pokes at the swift_reflection_infoForInstance() API
    of the SwiftRemoteMirror library.