Support per-package lib dirs for bundled apps

Bundled apps can now use /system/lib/apkname or /system/lib64/apkname
in addition to the (globally shared) /system/lib and /system/lib64
directories.  Note that when an app is updated post hoc the update APK
will look to its normal library install directory in
/data/data/[packagename]/lib, so such updates must include *all*
needed libraries -- the private /system/lib/apkname dir will not be in
the path following such an update.

"apkname" here is the base name of the physical APK that holds the
package's code.  For example, if a 32-bit package is resident on disk
as /system/priv-app/SettingsProvider.apk then its app-specific lib
directory will be /system/lib/SettingsProvider

Bug 13170859

Change-Id: Ic44cc75312f33d2f5d402a1c261b2eca3fe8badc