This is a step to enable signing a given target_files zip with release
keys.
When calling sign_target_files_apks.py, we will delete all the entries
under IMAGES/ in order to re-generate them (with the proper release
keys). In order to support that, we need to pack everything in need into
TF.zip.
Steps to test the CL.
a) Choose a target that has both AVB and DTBO enabled.
$ m dist
b) Check IMAGES/dtbo.img and PREBUILT_IMAGES/dtbo.img both exist in the
generated out/dist/TF.zip.
c) Remove the entries under IMAGES/ from the generated TF.zip.
$ zip -d TF.zip IMAGES/\*
d) Re-generate the images with TF.zip.
$ build/make/tools/releasetools/add_img_to_target_files.py TF.zip
e) Check that IMAGES/dtbo.img is re-generated, and it's identical to the
image in b). Note that by default the re-generated image will carry a
different footer, because of the random salt. This CL is verified by
specifying the same salt.
Bug: 38315721
Test: see above.
Change-Id: I0bdc4e1cd4800962dc3902ca550dad6a8ca56c78
c633ed0230