vold: restore 4.4 sdcard logic

Mount points in 4.4 are always fuse-wrapped to provide granular
permission. Unix file systems no longer need to be manually
fuse-wrapped by us.

Change-Id: I6885b0baeaae7c380ec32d410a70a4f53801157b
vold: Support external non-emulated storage

It tries to acess EMULATED_STORAGE_SOURCE which is not
defined if the device doesnt have an emulated storage

mkdirs() also needs to be valid for EXTERNAL_STORAGE

See also https://github.com/CyanogenMod/android_system_vold/commit/5ced6afb769f09ada6e3d1787a36c6f9f8469ed6

Change-Id: I6463979a06eab301acd59e815713abc3f550853f
Merge remote-tracking branch 'remotes/omnirom/android-4.4' into remotes/vold/android-4.4