Make "repo sync -j<count>" stop properly on Ctrl-C.

The threaded 'repo sync' implementation would very often freeze the
process when interrupted by the user with Ctrl-C. The only solution
being to kill -9 the process explicitly from another terminal.

The reason for this is best explained here:

This patch makes all helper sync threads 'daemon', which allows the
process to terminate immediately on Ctrl-C.

Note that this will forcefully kill all threads in case of interruption; this
is generally a bad thing, but:

  1/ This is equivalent to calling kill -9 in another terminal, which
     is the _only_ thing that can currently stop the process.

  2/ There doesn't seem to be a way to tell the worker threads to
     gently stop when they are in a blocking operation anyway (even
     in the non-threaded case).

+ Do the same for "repo status -j<count>".

Change-Id: Ieaf45b0eacee36f35427f8edafd87415c2aa7be4
2 files changed