classes/populate_sdk_ext: ensure eSDK can build without uninative enabled
We were relying on uninative being enabled in the build in which the
eSDK was being produced, which is not the case for example for OE-Core's
default configuration. Move the code that copies the uninative tarball
and writes the checksum to copy_buildsystem so that it happens early
enough for that part of the configuration to be set up when we do the
filtering (which requires running bitbake).
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
