Vendor CM Build: Allow parallelize the optimization of framework-res.apk

from: http://review.cyanogenmod.com/#/c/19170/

This change enhancement the optimization of cm ota package, allowing do the optimization of
framework-res.apk in a parallel way. The current script optimize first the
framework-res package and then the rest of packages with xargs in parallel. The framework-res
package can be processed with xargs in parallel copying all the packages to a temporally folder
to apply xargs (because opticharged need that the package is the current directory).
This shortens the time of optimization process, because while framework-res package is
optimized, the rest of processor cores can be optimizing other packages.

Change-Id: I047f8c01b066db99e4dcc8bcb2f30c72492e1af8