Move some jet tests under a eigen 3.3.0 version ifdef

Change-Id: I65c1749d987f9b0925daed277b1373a7e31bf54d

internal/ceres/jet_test.cc

diff --git a/internal/ceres/jet_test.cc b/internal/ceres/jet_test.cc
index 3c6e23c..6ae6ef7 100644
--- a/internal/ceres/jet_test.cc
+++ b/internal/ceres/jet_test.cc
@@ -761,6 +761,8 @@
   EXPECT_FALSE(IsNaN(a));
 }
 
+#if EIGEN_VERSION_AT_LEAST(3, 3, 0)
+
 // The following test ensures that Jets have all the appropriate Eigen
 // related traits so that they can be used as part of matrix
 // decompositions.
@@ -817,7 +819,6 @@
 }
 
 // ScalarBinaryOpTraits is only supported on Eigen versions >= 3.3
-#if EIGEN_VERSION_AT_LEAST(3, 3, 0)
 TEST(JetTraitsTest, MatrixScalarUnaryOps) {
   const J x = MakeJet(2.3, -2.7, 1e-3);
   const J y = MakeJet(1.7,  0.5, 1e+2);