Remove explicts void returns

src/Composer/Downloader/PerforceDownloader.php

@@ -87,8 +87,6 @@ class PerforceDownloader extends VcsDownloader
     public function getLocalChanges(PackageInterface $package, $path)
     {
         $this->io->writeError('Perforce driver does not check for local changes before overriding', true);
-
-        return;
     }
 
     /**

src/Composer/Util/Perforce.php

@@ -363,8 +363,6 @@ class Perforce
         while ($line !== false) {
             $line = fgets($pipe);
         }
-
-        return;
     }
 
     public function windowsLogin($password)