Add google-style checker to "arc lint"

Summary:
After we reached a consensus on code format, which follows exactly
Google's coding style, a natural follow-up is to have a style checker
that can handle stuffs beyond format.

Google already has a powerful style checker "cpplint.py" and,
luckily, phabricator already provides the built-in linter for it!
Next time with "arc lint" most style inconsistency will be detected
(but will not be fixed).

Also I copied cpplint.py to linters directory, which is mostly
because we may need the flexibility to make some modifications on
it for our own need.

Test Plan:
ran arc lint table/block_based_table_builder.cc to see the amazing
results.

Reviewers: haobo, sdong, igor, dhruba

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15369

linters/cpp_linter/PfffCppLinter.php

@@ -0,0 +1,68 @@
+<?php
+// Copyright 2004-present Facebook.  All rights reserved.
+
+class PfffCppLinter extends ArcanistLinter {
+  const PROGRAM      = "/home/engshare/tools/checkCpp";
+
+  public function getLinterName() {
+    return "checkCpp";
+  }
+  public function getLintNameMap() {
+    return array(
+    );
+  }
+
+  public function getLintSeverityMap() {
+    return array(
+    );
+  }
+
+  public function willLintPaths(array $paths) {
+    $program = false;
+    $ret_value = 0;
+    $last_line = system("which checkCpp", $ret_value);
+    if ($ret_value == 0) {
+      $program = $last_line;
+    } else if (file_exists(self::PROGRAM)) {
+      $program = self::PROGRAM;
+    }
+    if ($program) {
+      $futures = array();
+      foreach ($paths as $p) {
+        $futures[$p] = new ExecFuture("%s --lint %s 2>&1",
+          $program, $this->getEngine()->getFilePathOnDisk($p));
+      }
+      foreach (Futures($futures)->limit(8) as $p => $f) {
+
+        list($stdout, $stderr) = $f->resolvex();
+        $raw = json_decode($stdout, true);
+        if (!is_array($raw)) {
+          throw new Exception(
+            "checkCpp returned invalid JSON!".
+            "Stdout: {$stdout} Stderr: {$stderr}"
+          );
+        }
+        foreach($raw as $err) {
+          $this->addLintMessage(
+            ArcanistLintMessage::newFromDictionary(
+              array(
+                'path' => $err['file'],
+                'line' => $err['line'],
+                'char' => 0,
+                'name' => $err['name'],
+                'description' => $err['info'],
+                'code' => $this->getLinterName(),
+                'severity' => ArcanistLintSeverity::SEVERITY_WARNING,
+              )
+            )
+          );
+        }
+      }
+    }
+    return;
+  }
+
+  public function lintPath($path) {
+    return;
+  }
+}