Implement sharding and coordinator

Stop using std::hash for sharding (#99)

To make sure different configurations make sharding in the same way
stop using std::hash.

Update LLVM

836.0

Run strip --strip-unneeded on build/llvm/linux/*.a (#81)

829.0: Fix racey ProcessTest. (#69)

* Fix racey ProcessTest.

The signal may have been delivered to tested sh process after
a syscall to exit(0), so the tests may have been flaky.

* Added a FIXME for ProcessTest.Process*

791.5

Append non-direct arguments before non-cached.

766.10

Fix command tests on Mac.

766.3: Try to preallocate non-contiguous space also on Mac.

Otherwise we can get "No space left on device" error.

728.0

Fix typo in RPM spec.

727.0

Make some file cache checks less strict.