[2/2] Speed up boot dex opt on multicore devices.

Change-Id: I13630de9d75d13c0368d261b3564b787067b65b1

Patchset: 3
http://review.cyanogenmod.org/#/c/59908/
(cherry picked from commit c8dc7e3aadb38b257cb3eb6430310f0a2259864c)
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
(cherry picked from commit 0438f810c7e8e3c53850874c7bdb74ac43b2ec88)