Previously when comparing which of multiple possible routes to choose in
an ambiguous case, we looked at the specificity of the target of redirect
matches rather than the original match. This meant that if a redirect
used a whilecard, but redirected to a target that was a static path,
we'd cound the static path's specificity instead of the wildcard.
This change stores the specificity of the redirect on the RedirectInstruction.
Closes#5933
a038bb9ae3