add a performance benchmark for libziparchive

This patch adds two benchmarks that measure the performance of some
operations of libziparchive.

Both benchmarks are creating a temporary zip file containing file
names of uniformly distributed lengths.  The creation of the zip
file is not timed in the benchmarks.

- FindEntry_no_match tries to find an inexisting entry in the files
  of the zip archive, in order to force the code to examine all the
  files in the archive.

- Iterate_all_files uses the iterate function to list all the files
  in the archive.

Bug: N/A
Test: adb shell /data/ziparchive-benchmarks
Change-Id: Ibdb524ba1c5ae55caddf0416ebbc09f8b6df0021