Partial revert.
Merge topic 'target-objects-refactor' into next

b003f7f4 Partial revert.
Revert "cmGlobalGenerator: Make ComputeTargetObjects non-virtual"

This reverts commit 67dd2c6f3d9250e5089fec0f1289ae6315ec4715.
Merge topic 'target-objects-refactor' into next

c6ed80f0 Revert "cmGlobalGenerator: Make ComputeTargetObjects non-virtual"
cmGeneratorTarget: Don't store ObjectSources for object libraries.

Compute them on demand instead.
Merge topic 'target-objects-refactor' into next

c481fadc cmGeneratorTarget: Don't store ObjectSources for object libraries.