swift234

Revert "stdlib: Move the darwin String implementation over to use the ICU library."
Revert "Add test cases to exercise the native String vs cocoa buffer String path."
Revert "stdlib: Add back a test I removed"
Revert "stdlib: Fix hasPrefix,hasSuffix tests"
Revert "stdlib: Add documentation for the cached ascii collation tables"

This reverts commit 31493, 31492, 31491, 31490, 31489.

There are linking errors in SwiftExternalProjects (we probably have to link
against libicucore somewhere).

Swift SVN r31543