SignaturePattern: Add exception for meta annotations

SignaturePattern: Add exception for meta annotations

Upon meta annotation usage in signature patterns, lint warnings like the
following were issued during type parameter traversal:

  does not match because annotation @java.lang.annotation.Inherited
  has @Target{ElementType.ANNOTATION_TYPE} [Xlint:unmatchedTargetKind]

To avoid this, we now heuristically check if we are in a meta annotation
situation and, if so, permit it.

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>