Fix certain setting writes being incorrectly skipped.

If a value that previously had a very long value (over the 500 char
threshold) is now set to null, isRedundantSetValue would incorrectly
return true even though the value was changed.

Change-Id: Ia5304743024ec01024be98aa51ed260d38caf93c
Merge "Fix certain setting writes being incorrectly skipped." into cm-10.2
Merge branch 'cm-10.2' of git://github.com/CyanogenMod/android_frameworks_base into cd-4.3