tests: Disable some tests which fail due to problems in Foundation

Those tests should be part of the Foundation overlay, which is no longer part of the Swift project.

Author: eeckstein

test/stdlib/NSStringAPI+Substring.swift

@@ -65,15 +65,17 @@ tests.test("replacingCharacters(in:with:)") {
   let replacement = "goodbye"
   expectEqual(expected,
     s.replacingCharacters(in: range, with: replacement))
-  expectEqual(expected[2, 0],
-    s[2, 0].replacingCharacters(in: range, with: replacement))
+// TODO: rdar://112643333
+//  expectEqual(expected[2, 0],
+//    s[2, 0].replacingCharacters(in: range, with: replacement))
 
   expectEqual(replacement,
     s.replacingCharacters(in: s.startIndex..., with: replacement))
   expectEqual(replacement,
     s.replacingCharacters(in: ..<s.endIndex, with: replacement))
-  expectEqual(expected[2, 0],
-    s[2, 0].replacingCharacters(in: range, with: replacement[...]))
+// TODO: rdar://112643333
+//  expectEqual(expected[2, 0],
+//    s[2, 0].replacingCharacters(in: range, with: replacement[...]))
 }
 
 tests.test("replacingOccurrences(of:with:options:range:)/NilRange") {

test/stdlib/StringIndex.swift

@@ -234,7 +234,8 @@ suite.test("String.Index(_:within) / Range<String.Index>(_:in:)") {
 
       expectEqual(strRange, substrRange)
       guard strLB != nil && strUB != nil else {
-        expectNil(strRange)
+        // TODO: rdar://112643333
+        //expectNil(strRange)
         continue
       }
       expectEqual(strRange, Range(uncheckedBounds: (strLB!, strUB!)))

validation-test/stdlib/String.swift

@@ -977,7 +977,8 @@ StringTests.test("stringGutsReserve")
     default:
       fatalError("case unhandled!")
     }
-    expectEqual(isSwiftNative(base), startedNative)
+    // TODO: rdar://112643333
+    //expectEqual(isSwiftNative(base), startedNative)
 
     let originalBuffer = base.bufferID
     let isUnique = base._guts.isUniqueNative