Ensure special Dalvik annotations are kept

These optimization annotations are special in that we don't want them
to have RUNTIME retention, but we do want them to be visible to ART.
R8 already has special rules to handle them, but with R8 full mode
it still requires a minimal keep rule for the given reference.

This allows usage of annotations like @NeverCompile from fully optimized
platform targets like SystemUI.

Bug: 215417388
Test: m + compare SystemUIGoogle.odex w/ @NeverCompile annotations
Change-Id: Id14bcc7b6d0d6dd385c60cfbe4d31f295cbaa5dc