Issue #3330477: Make igbinary usable without needing module enabled.

composer.json

 {
     "name": "drupal/igbinary",
     "description": "Offers igbinary based serialization service.",
+    "license": "GPL-2.0-or-later",
     "type": "drupal-module",
-    "license": "GPL-2.0+",
     "support": {
         "issues": "https://www.drupal.org/project/issues/igbinary"
     },
     "require": {
         "ext-igbinary": "*",
         "ext-zlib": "*"
+    },
+    "autoload": {
+        "psr-4": {
+            "Drupal\\igbinary\\": "src"
+        }
     }
 }