overlay: remove emulated storage mountpoint
X3:improve i/o performance
Add camera prop permission
Add cache target for NEON optimization.Add flag to disable id match check for camera
Fix camera perms.Fix ext sdcard mounting
Update vold setup for 4.4
 Bring back the SECONDARY_STORAGE variable

This variable is a requirement in KK as newly introduced APIs
such as Context.getExternalFilesDirs uses it to retrieve
secondary storage locations on the device.