init: Forcefully mount system_ext on DAP devices if not present in fstab.

Bug: 150315914
Test: cuttlefish boots with system_ext missing from fstab
Change-Id: I99f292a070678b8a98500258af98129fbd81dfa7
Merged-In: I99f292a070678b8a98500258af98129fbd81dfa7
1 file changed