Parse fstab.goldfish file from ramdisk.img

This patch modifies the emulator to detect an fstab.goldfish
in ramdisk.img, and if present, use it to determine the exact
format of all partitions on the system.

This file should be present starting with Android 4.4 (KitKat).
The change is important because not all SDK system images have
the same settings, and it's hard to guess correctly from the
API level or kernel version.

This should make the emulator _much_ more reliable in the way it
setups partition images, in the wake of changing partition
formats during platform development (i.e. the format of the
cache partition has changed several times in AOSP and internal
trees, and not all development branches have the same value now,
this patch should make the emulator always select the right value
now, instead of getting it wrong in many cases).

BUG=15831221,15832082,15753975,15670063,15137521

Change-Id: I636784f7a28e3b546b859ca355fd5345abf14982
1 file changed