It's imported from test/mutex.c and adjusted to CTS.
BUG=chromium:624520
BRANCH=none
TEST=Test passed on stm32l476-geval and nucleo-f072rb. make -j buildall
Change-Id: I8cab0541ecbb1daa26b4d728fbd3e45e903ee512
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/360600
Reviewed-by: Chris Chen <twothreecc@google.com>
