Moved pthreads adapter work to feature-pthreads and removed it from master

Author: WyriHaximus

composer.json

@@ -22,8 +22,7 @@
     "phpunit/phpunit": "^6.0 || ^5.0 || ^4.8"
   },
   "suggest": {
-    "ext-eio": "^1.2",
-    "ext-pthreads": "^2.0"
+    "ext-eio": "^1.2"
   },
   "autoload": {
     "psr-4": {

src/Filesystem.php

@@ -23,10 +23,6 @@ public static function create(LoopInterface $loop, array $options = [])
             return static::setFilesystemOnAdapter(static::createFromAdapter(new Eio\Adapter($loop, $options)));
         }
 
-        if (extension_loaded('pthreads')) {
-            //return static::setFilesystemOnAdapter(static::createFromAdapter(new Pthreads\Adapter($loop, $options)));
-        }
-
         return static::setFilesystemOnAdapter(static::createFromAdapter(new ChildProcess\Adapter($loop, $options)));
     }