vold: Mount ext4/f2fs portable storage with sdcard_posix context

This commit is a forward port of following commits:

Author: Michael Stucki <mundaun@gmx.ch>
Change-Id: Ia34ad91444951e62f6d17374f480dcbdfa34cca3

Author: Tom Marshall <tdm@cyngn.com>
Change-Id: I05d9b57cc28ffd1f8deb8148d81c7f6fad0aa8db

Author: Pawit Pornkitprasan <p.pawit@gmail.com>
Change-Id: I1364f37018b25d79b1826c85849def64e868d72f

Author: Pawit Pornkitprasan <p.pawit@gmail.com>
Change-Id: I873af4dc2309d3d0942ce466b8acf8158abb85ae

Author: Jorge Ruesga <jorge@ruesga.com>
Change-Id: Ic0bb314b30e42489c45caec29d35d6896c9849eb

Signed-off-by: Michael Bestas <mikeioannina@cyanogenmod.org>
Change-Id: I9699643987c53d8e2538720f33da28de35230dfe
5 files changed