when forcing a GC, also sleep a little

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/GcModuleBuiltins.java

@@ -73,6 +73,11 @@ int collect(@SuppressWarnings("unused") Object level,
             gil.release(true);
             try {
                 PythonUtils.forceFullGC();
+                try {
+                    Thread.sleep(15);
+                } catch (InterruptedException e) {
+                    // doesn't matter, just trying to give the GC more time
+                }
             } finally {
                 gil.acquire();
             }