Add missing test fixture

tests/Composer/Test/Autoload/Fixtures/include_paths.php

@@ -0,0 +1,12 @@
+<?php
+
+// include_paths.php generated by Composer
+
+$vendorDir = dirname(__DIR__);
+$baseDir = dirname($vendorDir);
+
+return array(
+    $vendorDir . '/a/a/lib',
+    $vendorDir . '/b/b/library',
+    $vendorDir . '/c/library',
+);