dirname read in .spec.

src/recipe.cr

@@ -163,6 +163,8 @@ class Package::Recipe
 				@instructions.build << value.as_s_or_ls
 			when "install"
 				@instructions.install << value.as_s_or_ls
+			when "dirname"
+				@dirname = value.as_s
 			when "dependencies"
 				value.as_a_or_s.each do |atom|
 					@run_dependencies << atom