framework: packageinstaller :fix logical error in size calculation

fix logical error in available size calculation.

Change-Id: Ic6ce312cf1c146030a20187fcb27b24fbe4c321a
Revert "Reimplement ZipFileRO in terms of libziparchive."

This reverts commit afd31e08299008fdc5c2813f21b2573f29dc53df.

Conflicts:
	libs/androidfw/Android.mk