#5319 potential race condition when counting torrents

git-svn-id: svn://svn.transmissionbt.com/Transmission/trunk@14043 f4695dd4-2c0a-0410-b89c-da849a56a58e
r14044 Use OSAtomicIncrement32(&value) instead of OSAtomicAdd32(1, &value)

git-svn-id: svn://svn.transmissionbt.com/Transmission/trunk@14044 f4695dd4-2c0a-0410-b89c-da849a56a58e