sf: Enable swaprect optimization by default only on QCOMs

 * This is confirmed to cause problems at least on i9500.
 * Only enable it by default on QCOMs, other devices can opt
   in using the system property.

Change-Id: Ic00137201f4a5383877f4033473c1ea5ac32a3a7
[2/2] Speed up booting on multicore devices.

Add multithreading support.

Change-Id: I13630de9d75d13c0368d261b3564b787067b65b1