StringBuilder: Annotate local Android changes

This change annotates the Android changes in java/lang/StringBuilder.
After this change all the differences WRT OpenJDK8u121-b13
are annotated. No functional changes made.

Bug: 74379469
Bug: 79902155
Test: make droid
Change-Id: If727466b9babbf03da7738a64f4be6510292bd52
1 file changed