Update layoutlib following commit 66c6d78

Change I189306b7 introduced the use of ImageDecoder for creating
Bitmaps. This needs to be dealt with in layoutlib as this uses native
code.
As this does not change behaviour but is simply a performance driven
change, we simply delegate ImageDecoder back to BitmapFactory as was
done previously.

Test: layoutlib tests
Change-Id: I593b033c1a3dc77162b3d810e63f4b5f80d34ef5