Fix abi-detection for 32-bit system apps

Some system apps are still special and use symlinks
to /system/lib. For these apps we try to detect abi
based on directory structure if detecting abi the
regular way was failed.

Bug: 21668152
Bug: 21711506
Change-Id: Ic048e5f4c24d06ca2cb917d7a061a41bde597e9f