classes/populate_sdk_ext: add gdb to full extensible SDK
If SDK_EXT_TYPE is set to "full" then we really ought to be shipping
everything that is expected to be in the SDK, and that includes gdb
(it's already referred to by the environment setup script if nothing
else). This is implemented by using the SDK_INCLUDE_TOOLCHAIN
functionality I just added, since the only material thing that adds on
top of a full SDK is gdb and we should always have the rest of it in a
full SDK anyway.
Fixes [YOCTO #9850].
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
