If compiler has stack protector support, set
CONFIG_CC_STACKPROTECTOR_STRONG.

Reviewed-at: https://android-review.googlesource.com/#/c/238388/Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
[AmitP: cherry-picked this change from Android common kernel]
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>