Base: Factor out preference-in-storage check to overridable method.

taken from
https://github.com/CyanogenMod/android_frameworks_base/commit/e262881de4fd813bf876ff0b3f2a476d30a1b74d

need by
https://gerrit.omnirom.org/#/c/5759/

Change-Id: I64966e15e0e92a2058809ead2c694a9badae881b
[1/2] Base: Add an option to change the device hostname

This adds an option to modify the device hostname used
in ip resolution. This is useful when connecting to the
android device in a dynamic dhcp environment.

Change-Id: I56da8b49899e2a8c1a34bf8eee618e048ba7d82d
Merge pull request #2 from omnirom/android-4.4

merge