Floss: Add missing required packages to bootstrap script

This adds two required packages
- libabsl-dev
- liblc3-dev

Bug: 299597420
Test: run ./build.py --target clean && ./build.py --target bootstrap
Test: mma -j32
Tag: #floss
Change-Id: Id449f8f2396e6f0252c99ee7b687127d5652c7ef