Add memory leak test for ntt mult and newton division

Author: tompng

test/bigdecimal/test_vp_operation.rb

@@ -188,4 +188,14 @@ def test_vpdivd_intermediate_zero
       assert_vpdivd_equal([BigDecimal('1.00000499'), BigDecimal('1e-8')], [BigDecimal("2.00000999"), 2, 3])
     end
   end
+
+  def test_no_memory_leak_mult
+    omit unless ntt_mult_available?
+    assert_no_memory_leak("10000.times { BigDecimal('123456789.246913578').nttmult(BigDecimal('987654321.135792468')) }")
+  end
+
+  def test_no_memory_leak_div
+    omit unless ntt_mult_available?
+    assert_no_memory_leak("10000.times { BigDecimal('123456789.246913578').vpdivd_newton(BigDecimal('987654321.135792468'), 10) }")
+  end
 end