classes/buildhistory: split SDK data by IMAGE_NAME

classes/buildhistory: split SDK data by IMAGE_NAME

Data from SDKs produced from different images or different
meta-toolchain style recipes should go into separate directories,
since SDK_NAME doesn't include anything to differentiate these by
default (only pieces for the distro name and architectures).

Note you should delete or move existing data under the buildhistory/sdk/
directory manually after this change.

Fixes [YOCTO #4622].

(From OE-Core rev: 74658b66530184b0287152397341fbe411e90c71)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>