This patch prevents aspect functions from being evaluated when their
associated targets are incompatible. Otherwise aspects can generate
errors that should never be printed at all. For example, an aspect
evaluating an incompatible target may generate errors about missing
providers. This is not the desired behaviour.

The implementation in this patch short-circuits the `AspectValue`
creation if the associated target is incompatible.

I had tried to add an `IncompatiblePlatformProvider` to the
corresponding `ConfiguredAspect` instance, but then Bazel
complained about having duplicate `IncompatiblePlatformProvider`
instances.

Fixes  bazelbuild#15271

(cherry picked from commit 6d71850)

…-5.3