tests: Add array bounds check

Ensure that mock_keypresses_count is in bounds before accessing the
mock_keyflags array.

BUG=none
TEST=make clean && make runtests
BRANCH=none

Change-Id: Ifa8fce5438f2e2547c9e316038466244eee7bfa9
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Found-by: Coverity CID 198899
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/1752048
Reviewed-by: Joel Kitching <kitching@chromium.org>
1 file changed