Prefer property_contexts from /system & /vendor
This changes system_properties' initialize_properties to prefer
loading property_contexts from /system/etc/selinux &
/vendor/etc/selinux, while falling back to the pre-existing behavior
of loading from /.
Test: Device with *_property_contexts in / boots up fine, no denials
to do with properties, getprop -Z lists correct labels.
Test: Device with *_property_contexts in /system & /vendor, but not
in /, boots up fine, no denials to do with properties,
getprop -Z lists correct labels.
Test: Device with *_property_contexts in /system & vendor and with
empty *_property_contexts in / boots up fine, no denials to do
with properties, getprop -Z lists correct labels.
Bug:
36002573
Change-Id: I15174acdf89ee8f5a96acf1e38a54d4214df51ef