Run dex2oat from the staged apk directory.

The frameworks/base change makes the PackageManager pass relative paths
of previous code paths as shared library paths. This change passes the
base directory for these relative paths to dex2oat using the new switch
--classpath-dir.

Part of a multi-project change.

Bug: 34169257
Test: cts-tradefed run singleCommand cts -d --module
CtsAppSecurityHostTestCases -t android.appsecurity.cts.SplitTests

Change-Id: Ic20aa0b6a80104d0759ac84df3eb89570604e53f