Allow symlinks to be used in vold managed fstab entries

With device-tree kernels the sysfs path for SD cards varies depending on
device-tree layout and the actual card used. It is therefore impossible
to specify the sysfs path for the device in fstab.

However, there exists a symlink to the device which is created under a
generic path like '/sys/block/mmcblk0/device'. To use such a path with
vold we need to convert the symlinked path to the real path, which this
patch does.

Change-Id: I68e693772e70b758dab22fcd5f0eb4b9e84a2443
Signed-off-by: Jon Medhurst <tixy@linaro.org>
segfault THIS.

Change-Id: Id09d97c0f52d79c7695f8839406302b83d0da0fd
Ext4: SD card write access fix

chown everything to media_rw on ext4 forated sdcard

Change-Id: I01a5a82b24feb3e52849664e02c5acaed85fc2e3
Fix build.