Group dirty images objects together in the image.

Adds --dirty-image-objects switch to dex2oat to pass to image writer,
which takes in a list of dirty objects dumped by the new imgdump switch
--dump-dirty-objects. Currently that list of dirty objects contains
classes with dirty static fields.

Bins these classes into kBinKnownDirty, which are image objects that are
known to be dirty.

Measured fewer dirty pages at runtime via showmap:
systemui private dirty memory (kB):
492 -> 352 in boot-framework.art
204 -> 192 in boot.art
 96 ->  88 in boot-core-libart.art
systemserver private dirty memory (kB):
412 -> 304 in boot-framework.art
148 -> 132 in boot.art
100 ->  96 in boot-core-libart.art

Bug: 62554875
Test: mm test-art-host

(cherry picked from commit c23b0c04)

Change-Id: Ief11dee659cacf079ebf8848425532418c656a2a