framework: packageinstaller :fix logical error in size calculation

fix logical error in available size calculation.

Change-Id: Ic6ce312cf1c146030a20187fcb27b24fbe4c321a
Allow creating custom dialogs in DialogPreference.

This allows creating non-AlertDialogs while still using the click and
state handling of DialogPreference.

Change-Id: I54fd7d6d6b9f6a49fef1ae95e0178838b3edfa56