Add com.android.virt

com.android.virt is an APEX for virtual machine monitors like crosvm.
The APEX currently empty and isn't updatable.

Bug: 174633082
Test: m com.android.virt

Change-Id: I8acc8e147aadb1701dc65f6950b61701131f89d2
diff --git a/apex/com.android.virt-file_contexts b/apex/com.android.virt-file_contexts
new file mode 100644
index 0000000..83b4b58
--- /dev/null
+++ b/apex/com.android.virt-file_contexts
@@ -0,0 +1 @@
+(/.*)?                   u:object_r:system_file:s0