Add aggregated file storing all the results (#408)

Add aggregated file storing all the results (#408)

* Add aggregated file storing all the results

* Add dump result method, for viewing binary

Just show sizes, not contents

* Check the results rather than cache contents

This helps when changing the cache storage

* Rename cache struct to filelist instead

Now that it doesn't really store anything

* Add version and hash size to result header

* Copy files by buffer instead of by byte

* Make aggregated result files optional

This will guard the tests, until ready to integrate

* Fix clang warning about unused macros

* Stray comma in configure broke the Mac build

* Avoid freeing the provided structure

* Avoid getting result from cache twice

* Fix partial read/write after rewrite

* Add test cases for aggregated result

* Fix wrong suffix for the depend file

* Read the .stderr with the rest of result

* Fix test suite only being run for clang

* Respect the compression level for result