build_packages: Add flag for deleting existing sysroot

The existing process for starting with a clean sysroot requires
either manually deleting it or running setup_board --force. The
extra step is unnecessary, especially since we want to move
developers away from setup_board.

TEST=./build_packages --cleanbuild --board=betty

Change-Id: I0cb1958ce3964cfa13b4905c7360fc16e6b14b2b
Tested-by: Alex Klein <>
Commit-Queue: Chris McDonald <>
Reviewed-by: Chris McDonald <>
1 file changed