Add a varargs rewriting test

test/tests/varargs_ics.py

+# run_args: -n
+# statcheck: 1 <= noninit_count("slowpath_runtimecall") < 20
+
+# Make sure we can patch some basic varargs cases
+
+def f(*args):
+    print sum(args)
+
+def f2(a, b, c, d, e, *args):
+    print sum(args)
+
+for i in xrange(1000):
+    f(10001)
+    f(-1252, 1239)
+    f(0, 839, 999)
+    f2(1, 2, 3, 4, 5, 6, 7, 8)