Avoid invoking sdk member to add empty list of dependencies

Simplifies debugging sdk membership code when it is only called if an
appropriate member is present.

Test: m nothing
Change-Id: I32bc93e0484c829bdbd6b050822249feb6404f89

sdk/sdk.go

@@ -323,8 +323,10 @@ func memberMutator(mctx android.BottomUpMutatorContext) {
 		if s.Enabled() {
 			for _, memberListProperty := range s.memberListProperties() {
 				names := memberListProperty.getter(s.dynamicMemberTypeListProperties)
-				tag := memberListProperty.dependencyTag
-				memberListProperty.memberType.AddDependencies(mctx, tag, names)
+				if len(names) > 0 {
+					tag := memberListProperty.dependencyTag
+					memberListProperty.memberType.AddDependencies(mctx, tag, names)
+				}
 			}
 		}
 	}