List SHA-1 digests of APK entries' contents in .SF files.

Due to a bug introduced in 8562fd47
SHA-1 digests of APK entries' contents were listed under wrong
attribute name. The effect is equivalent to not listing SHA-1
digests.

This change fix the issue by listing SHA-1 digests under the correct
attribute name. However, these digests are not that useful because:
(1) typically the digest of the MANIFEST.MF verifies and thus the
per-entry digests are ignored, and (2) per-entry digests of entries
with names longer than 64 characters are wrong in any case because the
digest generation code does not take into account that such names are
split over multiple lines.

An alternative to this change would be to completely omit outputting
per-entry sections of .SF files, thus saving space and speeding up APK
verification (.SF files would decompress faster).

Bug: 26513901
Change-Id: If95d58e9baa62b1113639fe70724e1e9c9f4e15c