message: Make feature_column_test.py run with the C API enabled.
  I only enabled running the C API with test classes that other testing
  found failures in to avoid increasing the test time unnecessarily.
diff: @@ -1072,6 +1072,7 @@ def get_linear_model_column_var(column):
  'linear_model/' + column.name)[0]
  +@test_util.with_c_api
  class LinearModelTest(test.TestCase):
  def test_raises_if_empty_feature_columns(self):
  @@ -1325,6 +1326,12 @@ class LinearModelTest(test.TestCase):
  price = fc.numeric_column('price', shape=2)
  with ops.Graph().as_default():
  features = {'price': [[1.], [5.]]}
  + if ops._USE_C_API:
  + with self.assertRaisesRegexp(
  + Exception,
  + r'Cannot reshape a tensor with 2 elements to shape \[2,2\]'):
  + predictions = fc.linear_model(features, [price])
  + else:
  predictions = fc.linear_model(features, [price])
  with _initialized_session():
  with self.assertRaisesRegexp(Exception, 'requested shape has 4'):
  @@ -1791,6 +1798,7 @@ class InputLayerTest(test.TestCase):
  self.assertAllEqual([[2, 2], [2, 2], [2, 2]], gradient)
  +@test_util.with_c_api
  class FunctionalInputLayerTest(test.TestCase):
  def test_raises_if_empty_feature_columns(self):
  @@ -1855,6 +1863,12 @@ class FunctionalInputLayerTest(test.TestCase):
  price = fc.numeric_column('price', shape=2)
  with ops.Graph().as_default():
  features = {'price': [[1.], [5.]]}
  + if ops._USE_C_API:
  + with self.assertRaisesRegexp(
  + Exception,
  + r'Cannot reshape a tensor with 2 elements to shape \[2,2\]'):
  + net = fc.input_layer(features, [price])
  + else:
  net = fc.input_layer(features, [price])
  with _initialized_session():
  with self.assertRaisesRegexp(Exception, 'requested shape has 4'):
  