[master] Exclude R2RDump from source-build

[dagood]

This should remove the Microsoft.NETCore.CoreDisTools/1.0.1-prerelease-00005 prebuilt dependency.

Context at #1816 for why we can exclude R2RDump.

[dagood]

Confirmed in local build that it's removed from production + tarball build.

<BaselineComparison>
  <Removed>
...
    <PackageIdentity Id="Microsoft.NETCore.CoreDisTools" Version="1.0.1-prerelease-00005" />
...
    <PackageIdentity Id="runtime.placeholder-rid.Microsoft.NETCore.CoreDisTools" Version="1.0.1-prerelease-00005" />
...
  </Removed>
</BaselineComparison>

Forgot to make the change to the baselines to verify this in PR validation, but I'm going to avoid making that change here so I don't reset CI. (Unless I also need to make some other change.)

[dseefeld]

@dagood Can this be closed in favor of #1822?

[dagood]

Yep, this package shows up as removed in the prebuilt data for #1822.