lib: Remove unused var+operations in util.inspect

This was originally introduced in 6034701 to prevent the closing
brace being pushed onto the next line if an object is longer than
the max width, however the functionality was removed in d164989 but
the supplementary variables (and operations) were left behind

lib/util.js

@@ -424,10 +424,7 @@ function formatProperty(ctx, value, recurseTimes, visibleKeys, key, array) {
 
 
 function reduceToSingleString(output, base, braces) {
-  var numLinesEst = 0;
   var length = output.reduce(function(prev, cur) {
-    numLinesEst++;
-    if (cur.indexOf('\n') >= 0) numLinesEst++;
     return prev + cur.replace(/\u001b\[\d\d?m/g, '').length + 1;
   }, 0);