cross-canadian: Update after PN changes to include TARGET_ARCH
This patch massively simplifies the canadian packaging and allows
multiple toolchain targets to be parallel installed into the same
nativesdk sysroot without package name conflits. Since we now do
this, we can simplify cross-canadian to become more like nativesdk.
This is a first pass over this task, similar changes would be
desireable to cross and the whole MULTIMACH_ARCH mess can then
probably be similified much further.
