Add metadata files for itertools. am: 20d7a6fa89 am: a3fb21f89d am: dac361d45c am: 0099efedb2

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/itertools/+/1621382

Change-Id: Ifc4ff2c34ea250d065ce9b7063192edc952dd1ef