Add bitbake's target for cross SDK

Add recipe for a basic cross SDK image for baseline of AGL Distribtuion
for IVI profile.

To build SDK,
   $ bitbake agl-image-ivi-crosssdk

To install SDK (e.g. for porter),
   $ cd tmp/deploy/sdk
   $ ./poky-agl-glibc-x86_64-agl-ivi-image-crosssdk-cortexa15hf-vfp-neon-toolchain-1.0.0.sh

To use SDK (e.g. for porter),
   $ source /opt/poky-agl/1.0.0/environment-setup-cortexa15hf-vfp-neon-poky-linux-gnueabi

Change-Id: If0d55026dfc53ce45ed8e73fc9d996cad85771b1
Signed-off-by: Tadao Tanikawa <tanikawa.tadao@jp.panasonic.com>