Add SuppressLint to framework-annotations-lib

Not having this on the classpath causes metalava to ignore
@SuppressLint annotations on APIs.

(The annotation has CLASS retention).

Bug: 172266358
Test: m <framework-module>-check-current-api (with suppressions)
Change-Id: I4aeecf6f067f5c141c6f2a31c9e8b46df3ff7e6a