[cdc_rsync] Enable local syncing (#75)

Adds support for local syncs of files and folders on the same Windows
machine, e.g. cdc_rsync C:\source C:\dest. The two main changes are

- Skip the check whether the port is available remotely with PortManager.
- Do not deploy cdc_rsync_server.
- Run cdc_rsync_server directly, not through an SSH tunnel.

The current implementation is not optimal as it starts
cdc_rsync_server as a separate process and communicates to it via a
TCP port.

fastcdc/fastcdc.h

@@ -240,7 +240,7 @@ class ChunkerTmpl {
     }
 
     // Init hash to all 1's to avoid zero-length chunks with min_size=0.
-    uint64_t hash = (uint64_t)-1;
+    uint64_t hash = UINT64_MAX;
     // Skip the first min_size bytes, but "warm up" the rolling hash for 64
     // rounds to make sure the 64-bit hash has gathered full "content history".
     size_t i = cfg_.min_size > 64 ? cfg_.min_size - 64 : 0;