ucs2: Add no_std variant am: 5c85611486

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/ucs2/+/3361546

Change-Id: I820630d2fe36caa91852571bd77660581891bf7e
Signed-off-by: Automerger Merge Worker <[email protected]>