Add target argument to tag rule invocations so that tag rules can get infmration on the specific target they are naming. This is useful, for eaxmple, in finding the sources and basing name changes on that.

src/build/virtual-target.jam

@@ -446,9 +446,8 @@ class abstract-file-target : virtual-target
                     errors.error <tag>@rulename is present but is not the only
                         <tag> feature. ;
                 }
-
                 self.name = [ indirect.call $(rule-name) $(specified-name)
-                    : $(self.type) : $(ps) ] ;
+                    : $(self.type) : $(ps) : $(__name__) ] ;
             }
             else
             {