Unify zipfile implementations : Step 1.

Extract zip file processing logic from libdvm into a
standalone library.

This library is a stricter than the libdvm library in
several ways:
- Duplicate zip entry names are now disallowed. Files with
  such entries will fail to parse.
- We now verify CD file size information with the individual
  file header information. (This was pointed out as a deficiency
  of this implementation in past discussions.)
- We also add support for crc checking, which means we might
  need to parse the optional data descriptor footer (if one
  exists).

We also provide an API for iterating over the entries of
a zip file. This library is optimized for two use cases :

- Lookup for a single entry in the file, with the intention
  of processing or extracting the data associated with that
  entry
- Iterating over all entries in a file *and* processing
  / extracting their data.

Change-Id: Ia87de6184ef753cc470b0af755c47a4f92ac8198
Fix return code for ended iteration.

The API promises a return code of -1 for an
ended iteration and lower negative values for
errors.

Change-Id: I688a1ee2efad1bdfc6959cf27e49c0426ebf27f8
Add unit tests for libziparchive.

- Add a build rule for host tests
- Add basic tests for Find / Iterate and Extract
  for both deflated & stored entries.
- Fix an off by one error that the test uncovered.

Change-Id: If72009b1ea9791d5a265829f05c32ffe1c2752c4
Use FileMap from libcutil instead of rolling our own.

Adds windows support as a side effect.

Change-Id: I912c1f980f284d01d4f3936291999646ddf6250a
Get rid of some log spam.

We don't need a warning if an entry isn't found in a zip
file. It can happen as part of normal operation.

Change-Id: I86c132a040371f36f0dd981b49c02b3173821439