Avoid extra trailing whitespace in stdout mode

Not only does `console.log()` already print a newline after its output,
but it prints a space between each of its arguments, so including `'\n'`
as a second argument results in a trailing space, then a newline, then
another newline. Excluding this extra `'\n'` results in just one newline
after the data.

lib/svgo/coa.js

@@ -420,7 +420,7 @@ function processSVGData(config, info, data, output, input) {
  */
 function writeOutput(input, output, data) {
     if (output == '-') {
-        console.log(data, '\n');
+        console.log(data);
         return Promise.resolve();
     }
     return writeFile(output, data, 'utf8').catch(error => checkWriteFileError(input, output, data, error));