Greylist APIs which apps can resolve to at runtime

This applies to SpannableString methods:
 - charAt(I)C
 - getChars(II[CI)V
 - getSpanEnd(Ljava/lang/Object;)I
 - getSpanFlags(Ljava/lang/Object;)I
 - getSpanStart(Ljava/lang/Object;)I
 - getSpans(IILjava/lang/Class;)[Ljava/lang/Object;
 - length()I
 - nextSpanTransition(IILjava/lang/Class;)I
(these are all already in the greylist)

and one method from android.app.backup.FileBackupHelperBase:
 - writeNewStateDescription(Landroid/os/ParcelFileDescriptor;)V
(added in this CL).

We won't fix this properly in P, so greylist the uses for now.

Bug: 64382372
Bug: 76424618
Test: make
Change-Id: I4c4ef13338b1fa2f7f21c07c63d88d3559d10341