give a bit more time for c member access

Author: timfel

mx.graalpython/mx_graalpython_bench_param.py

@@ -89,7 +89,7 @@
     'special-add': ITER_15 + ['5'],
     'special-len': ITER_10 + ['5'],
     'member_access': ITER_10 + ['5'],
-    'c_member_access': ITER_10 + ['5'],
+    'c_member_access': ITER_25 + ['5'],
 }