[libc++] Revert "[SystemZ][z/OS] Missing wchar functions libc++"

This reverts commit febbf68b423b14d55a14980d2ba3ec37ef1e31dc because it
added files that were not under the LLVM license.

See https://reviews.llvm.org/D98207 for details.

GitOrigin-RevId: 1e337b1dd90369763ebe6aa4eb3e563c61ddb213
4 files changed