Fix runtest --path for package-private frameworks tests.

A recent change to runtest resulted in absolute paths incorrectly
being used for a tests build path. This broke the special logic
for frameworks/base tests, since it assumed relative build paths.
Change build paths back to relative paths.

Bug 5105885

Change-Id: I83a26be25294d501cca73eb1b88a7364131b2caf
4 files changed