Build sepolicy files for microdroid_vendor

microdroid_vendor is the vendor.img for microdroid. We need
microdroid_vendor.img and sepolicy files in it because init demands the
files during the boot process. Since microdroid_vendor.img is a Soong
module, the sepolicy files in it should be built with Soong as well.

Note that, these Soong modules are configured only for microdroid. In
the future, we will generalize this so that ordinary Android can use
the Soong-build sepolicy files.

Bug: 180986662
Test: m microdroid_vendor
Change-Id: I88eec6e1fbf687301366d5c814265131c8d3fdbb
1 file changed