Move prefix configuration to configuration file

Author: sebastianbergmann

build.xml

@@ -327,8 +327,6 @@
             <arg value="--no-interaction" />
             <arg value="--output-dir" />
             <arg path="${basedir}/build/tmp/phar-scoped" />
-            <arg value="--prefix" />
-            <arg value="PHPUnit" />
             <arg path="${basedir}/build/tmp/phar" />
         </exec>
 

build/config/php-scoper.php

@@ -9,6 +9,8 @@
  */
 
 return [
+    'prefix' => 'PHPUnit',
+
     'exclude-namespaces' => [
         'PHPUnit',
         'Prophecy'