It's imported from test/hooks.c and adjusted to CTS.
BUG=chromium:624520
BRANCH=none
TEST=make buildall. Test passed on stm32l476-geval and nucleo-f072rb.
Change-Id: I70673f2c0f8316a2b1fd9472eeb7db350fdc2d84
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/360631
Reviewed-by: Chris Chen <twothreecc@google.com>
