Add required BY_EXCEPTION_ONLY header comment. am: 1ee4a096eb

Original change: https://android-review.googlesource.com/c/platform/external/ms-tpm-20-ref/+/1559290

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I0bd4667f69c04d7756219c5d372daf2a811eb95b