Therefore InstallPackage() doesn't need to worry about the details of a
given Package.
Bug: 127071893
Test: run update from /bin/recovery --update_package=@path, sideload a package
Change-Id: I0caa36785b43924f884ee398e7ea640d7472a92e
Build libinstall as a shared library. Also drop the dependency on the
global variables in common.h.
Test: unit tests pass, sideload an OTA
Change-Id: I30a20047768ce00689fc0e7851c1c5d712a365a0