e2fsdroid: Don't over-reserve blocks for files in Base FS.

If a large number of blocks move from one file to another file,
e2fsdroid will inadvertently reserve the moved blocks for the source
file. If the larger file is visited first, it can fail to acquire blocks
because they're reserved by the smaller file.

This patch only reserves the first N blocks of a file in Base FS, where N
is large enough to satisfy the |st_size| property from lstat(2). We only
consider "owned" blocks rather than deduplicated blocks, in case the new
file cannot be deduplicated.

Bug: 145316683
Test: e2fsdroid with dynamic partitions
Change-Id: I32e255a19550d52d90342c21d7218981108a71b1
1 file changed