scripts: set default CFLAGS to optimise.

The extra CFLAGS override the product defaults, causing the product to
be built without optimisation or debug. Be explicit and add these in.

Reported-by: Johannes Stezenbach <js@sig21.net>
Signed-off-by: Michael Hope <michael.hope@linaro.org>
Message-Id: <CANLjY-=3Gbio6nzUPhhevDHV7cUN=6Vigooe9nSf-RnGCqnjog@mail.gmail.com>
Patchwork-Id: 198808

 # This file declares functions for bare metal kernel (IE. none)

 # Copyright 2008 Yann E. MORIN

 # Licensed under the GPL v2. See COPYING in the root of this package

 CT_DoKernelTupleValues() {

     # For bare-metal, there is no kernel part in the tuple

     CT_TARGET_KERNEL=

 }

 do_kernel_get() {

     :

 }

 do_kernel_extract() {

     :

 }

 do_kernel_headers() {

     :

 }