setup_board: Fix LIBC_VERSION persistence.

When running setup_board with --regen_config, we persist LIBC_VERSION's
value by appending it to make.conf.board_setup.
If make.conf.board_setup, doesn't have a new line at the end, this will
create a bash file that will not parse.

BUG=brillo:662
TEST=setup_board --regen_configs don't fail anymore.

Change-Id: I9177f48dc2c97061da27976448f45b1bcd291eea
Reviewed-on: https://chromium-review.googlesource.com/262741
Trybot-Ready: Bertrand Simonnet <bsimonnet@chromium.org>
Tested-by: Bertrand Simonnet <bsimonnet@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Bertrand Simonnet <bsimonnet@chromium.org>
1 file changed