anchor.diff:          Assert.AreEqual(BigInteger.GreatestCommonDivisor(bigPositiveA, bigPositiveB), 900000000090I)
           Assert.AreEqual(BigInteger.GreatestCommonDivisor(bigNegativeA, bigNegativeB), 900000000090I)
           Assert.AreEqual(BigInteger.GreatestCommonDivisor(0I, bigPositiveA), bigPositiveA)
  -#if MONO // see https://bugzilla.xamarin.com/show_bug.cgi?id=22591
  +#if CROSS_PLATFORM_COMPILER // see https://bugzilla.xamarin.com/show_bug.cgi?id=22591
   #else
           Assert.AreEqual(BigInteger.GreatestCommonDivisor(BigInteger(), bigPositiveA), bigPositiveA)
           Assert.AreEqual(BigInteger.GreatestCommonDivisor(bigPositiveA, BigInteger()), bigPositiveA)
  
positive.code:         Assert.IsTrue( (z1 = z1) )
          Assert.IsTrue( (z2 = z2) )
          Assert.IsTrue( (z3 = z3) )
  #if MONO // see https://bugzilla.xamarin.com/show_bug.cgi?id=22591
  #else
          Assert.IsTrue( (z4 = z4) )
  #endif
  
negative.code:         Assert.AreEqual((123I / 124I),0I)
          Assert.AreEqual((123I / (-124I)),0I)
          Assert.AreEqual((0I / 123I),0I) 
  #if CROSS_PLATFORM_COMPILER // see https://bugzilla.xamarin.com/show_bug.cgi?id=22591
  #else
          Assert.AreEqual((BigInteger() / 123I),0I)
  #endif
  