test: use common.skip for tap skip output

These were missed from 52bae222a3

PR-URL: https://github.com/nodejs/node/pull/8841
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

test/parallel/test-fs-readfile-pipe-large.js

@@ -6,7 +6,7 @@ var path = require('path');
 // simulate `cat readfile.js | node readfile.js`
 
 if (common.isWindows || common.isAix) {
-  console.log(`1..0 # Skipped: No /dev/stdin on ${process.platform}.`);
+  common.skip(`No /dev/stdin on ${process.platform}.`);
   return;
 }
 

test/parallel/test-fs-readfile-pipe.js

@@ -5,7 +5,7 @@ var assert = require('assert');
 // simulate `cat readfile.js | node readfile.js`
 
 if (common.isWindows || common.isAix) {
-  console.log(`1..0 # Skipped: No /dev/stdin on ${process.platform}.`);
+  common.skip(`No /dev/stdin on ${process.platform}.`);
   return;
 }
 

test/parallel/test-fs-readfilesync-pipe-large.js

@@ -6,7 +6,7 @@ var path = require('path');
 // simulate `cat readfile.js | node readfile.js`
 
 if (common.isWindows || common.isAix) {
-  console.log(`1..0 # Skipped: No /dev/stdin on ${process.platform}.`);
+  common.skip(`No /dev/stdin on ${process.platform}.`);
   return;
 }