Policy clarified: No need to share a "distribution medium"

Including code built from restricted sources in a distribution medium
does not require sharing the code for building the distribution medium.

Test: m cts dist

Test: m cts dist gts (requires cherry-pick to internal)

Change-Id: I7fcd889b11a97f8deaf4de9d72fdadd09deebe30

tools/compliance/readgraph.go

@@ -198,6 +198,9 @@ type targetNode struct {
 
 	// resolution identifies the set of conditions resolved by acting on the target node.
 	resolution LicenseConditionSet
+
+	// pure indicates whether to treat the node as a pure aggregate (no internal linkage)
+	pure bool
 }
 
 // addDependencies converts the proto AnnotatedDependencies into `edges`