Make rbc-run accept a makefile instead of a product

Needed for the board configuration.

rbc-run will also now pass any extra arguments it receives
to rbcrun. (The real program, not the script)

Bug: 201700692
Test: rbc_product_config.py aosp_arm64-userdebug
Change-Id: Ic9869f693f1d28bafee59050b6ae7b1fba14dbdd