Only append build interface include dirs to particular targets.

We shouldn't set the property on all custom targets.
Ensure that the build interface includes have been added.

This also means that we don't need to invoke AppendBuildInterfaceIncludes
in the GlobalGenerator.
Merge topic 'minor-fixes' into next

3851e0a Ensure that the build interface includes have been added.
fecede0 Only append build interface include dirs to particular targets.