Revert "stdlib: Fix hasPrefix,hasSuffix tests"

Revert "stdlib: Add back a test I removed"
Revert "Add test cases to exercise the native String vs cocoa buffer String path."
Revert "stdlib: Move the darwin String implementation over to use the ICU library."

This reverts commit r31477, r31476, r31475, r31474.

Commit r31474 broke the ASAN build.

Swift SVN r31488

validation-test/stdlib/Algorithm.swift

@@ -28,10 +28,12 @@ Algorithm.test("min,max") {
   // condition.
 }
 
-Algorithm.test("sorted/strings") {
+Algorithm.test("sorted/strings")
+  .xfail(.LinuxAny(reason: "String comparison: ICU vs. Foundation"))
+  .code {
   expectEqual(
-    [ "apple", "Banana", "cherry" ],
-    [ "cherry", "Banana", "apple" ].sort())
+    [ "Banana", "apple", "cherry" ],
+    [ "apple", "Banana", "cherry" ].sort())
 
   let s = ["apple", "Banana", "cherry"].sort() {
     $0.characters.count > $1.characters.count