check_elf_alignment.sh: extract APEXes

Understand APEXes.

It would be nice if it also recursively searched for APEXes and APKs
and '.apks' files and reported everything nested inside, but this is
what we have for now :)

Bug: N/A
Test: manual
Change-Id: I00898854b17c708e99c3ae336d15ffcf4eeeafea
1 file changed