post_build_ninja_summary.py gives a summary of a ninja build. It can be
run standalone or it can be run automatically by autoninja. This CL
updates the Python script and the autoninja bash script to make this
work on Linux. This includes removing a zero-value assert, and ensuring
that .so files get categorized as such.

Change-Id: I2d59ab129f5ce70117beeb119719f8432bfbab7c
Reviewed-on: https://chromium-review.googlesource.com/915053Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>