classes: Fixed the problem of undefined variables when compiling meta-toolchain.
The product name when compiling meta-toolchain is:
poky-glibc-x86_64-${IMAGE_BASENAME}-cortexa57-qemuarm64-toolchain-3.1+snapshot.host.manifest
poky-glibc-x86_64-${IMAGE_BASENAME}-cortexa57-qemuarm64-toolchain-3.1+snapshot.target.manifest
poky-glibc-x86_64-${IMAGE_BASENAME}-cortexa57-qemuarm64-toolchain-3.1+snapshot.testdata.json
poky-glibc-x86_64--cortexa57-qemuarm64-toolchain-3.1+snapshot.sh
inherit image-artifact-names to solve this problem.
Signed-off-by: Zang Ruochen <zangrc.fnst@cn.fujitsu.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
