Fix oat_writer to use WriteData which updates checksum.

OatWriter was using WriteFully in some places instead.

Bug: 28874264

(cherry-picked from commit 5e7cbde3100b0bfb58277accc9d71a94636ea727)

Change-Id: I7dac3ad0597c210ba6e12e0cc1670277d7a28fc7
1 file changed