populate_sdk_base.bbclass: Make it possible to override the create_shar method of...

populate_sdk_base.bbclass: Make it possible to override the create_shar method of populate_sdk_base.

If you wish to change the install/unpack method of the sdk, this can now be done by making
your own create_shar method, and setting a SDK_PACKAGING_FUNC variable to your
new create_shar function.

(From OE-Core rev: 3955c8eced352226bb4c9ceb710dbe02474b9024)

Signed-off-by: Thomas Kristensen <thkriste@cisco.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>