forward deriv for backwards of celu, elu, selu added

Author: Sam Andow

test/test_ops.py

@@ -1159,12 +1159,10 @@ def test_vjpvmap(self, device, dtype, op):
         xfail('nn.functional.bilinear', ''),
         xfail('nn.functional.binary_cross_entropy', ''),
         xfail('nn.functional.binary_cross_entropy_with_logits', ''),
-        xfail('nn.functional.celu', ''),
         xfail('nn.functional.cross_entropy', ''),
         xfail('nn.functional.cross_entropy', 'mean'),
         xfail('nn.functional.cross_entropy', 'none'),
         xfail('nn.functional.cross_entropy', 'sum'),
-        xfail('nn.functional.elu', ''),
         xfail('nn.functional.embedding', ''),
         xfail('nn.functional.embedding', 'functorch'),
         xfail('nn.functional.embedding_bag', ''),
@@ -1183,7 +1181,6 @@ def test_vjpvmap(self, device, dtype, op):
         xfail('nn.functional.pad', 'circular'),
         xfail('nn.functional.pairwise_distance', ''),
         xfail('nn.functional.prelu', ''),
-        xfail('nn.functional.selu', ''),
         xfail('nn.functional.softmin', ''),
         xfail('nn.functional.softmin', 'with_dtype'),
         xfail('nn.functional.softplus', ''),