Automated patching.

src/recipe.cr

@@ -243,6 +243,17 @@ class Package::Recipe
 					]
 				)
 
+				raise ExtractionError.new self, url unless status.success?
+			elsif basename.match /\.patch$/
+				@context.info "Applying '#{url.filename}'"
+
+				status = @context.run(
+					"#{building_directory}/#{dirname}",
+					"patch", [
+						"#{@context.sources_directory}/#{url.filename}"
+					]
+				)
+
 				raise ExtractionError.new self, url unless status.success?
 			else
 				@context.info "Copying '#{url.filename}'"