apexd is using following additional ioctl cmds to mount the mini
filesystem inside APEXs:

 LOOP_SET_STATUS64
 LOOP_SET_FD
 LOOP_SET_BLOCK_SIZE
 LOOP_SET_DIRECT_IO
 LOOP_CLR_FD

Test: m; m apex.test; adb push <the_built_apex> /data/apex; adb reboot

/apex/com.android.example.apex exists

Change-Id: I68388cc4f323e4fcff370c8cdc0958cbd827e9cc