Fixup UseProjectReferences

Author: wtgodbe

eng/targets/ResolveReferences.targets

@@ -47,6 +47,7 @@
       We don't use project references between components in servicing builds between compontents to preserve the baseline as much as possible.
     -->
     <UseProjectReferences Condition=" '$(UseProjectReferences)' == '' AND '$(IsServicingBuild)' != 'true' ">true</UseProjectReferences>
+    <UseProjectReferences Condition=" '$(UseProjectReferences)' == '' AND '$(IsTargetingPackBuilding)' == 'true' ">true</UseProjectReferences>
     <UseProjectReferences Condition=" '$(UseProjectReferences)' == '' AND '$(IsImplementationProject)' != 'true' ">true</UseProjectReferences>
     <UseProjectReferences Condition=" '$(UseProjectReferences)' == '' ">false</UseProjectReferences>