ext: Updated Pybind11 to version 2.4.1.

This updates Pybind11 from version 2.2.1 to version 2.4.1. This fixes
warning/error received when "<experiment/optional>" is used when
compiling using c++14 with clang. It should be noted that
"ext/pybind11/include/pybind11/std.h" has been changed to include a fix
added by commit ba42457254. This is
necessary to avoid build errors.

Built: Linux (gcc, c++11) and MacOS (clang, c++14).
Tested: Ran quick tests for X86, ARM, and RISC-V.
Deprecates: https://gem5-review.googlesource.com/c/public/gem5/+/21019
Change-Id: Ie9783511cb6be50136076a55330e645f4f36d075
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21119
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

ext/pybind11/tests/test_numpy_array.py

@@ -7,6 +7,21 @@ with pytest.suppress(ImportError):
     import numpy as np
 
 
+def test_dtypes():
+    # See issue #1328.
+    # - Platform-dependent sizes.
+    for size_check in m.get_platform_dtype_size_checks():
+        print(size_check)
+        assert size_check.size_cpp == size_check.size_numpy, size_check
+    # - Concrete sizes.
+    for check in m.get_concrete_dtype_checks():
+        print(check)
+        assert check.numpy == check.pybind11, check
+        if check.numpy.num != check.pybind11.num:
+            print("NOTE: typenum mismatch for {}: {} != {}".format(
+                check, check.numpy.num, check.pybind11.num))
+
+
 @pytest.fixture(scope='function')
 def arr():
     return np.array([[1, 2, 3], [4, 5, 6]], '=u2')
@@ -135,8 +150,18 @@ def test_make_c_f_array():
     assert not m.make_f_array().flags.c_contiguous
 
 
+def test_make_empty_shaped_array():
+    m.make_empty_shaped_array()
+
+    # empty shape means numpy scalar, PEP 3118
+    assert m.scalar_int().ndim == 0
+    assert m.scalar_int().shape == ()
+    assert m.scalar_int() == 42
+
+
 def test_wrap():
     def assert_references(a, b, base=None):
+        from distutils.version import LooseVersion
         if base is None:
             base = a
         assert a is not b
@@ -147,7 +172,10 @@ def test_wrap():
         assert a.flags.f_contiguous == b.flags.f_contiguous
         assert a.flags.writeable == b.flags.writeable
         assert a.flags.aligned == b.flags.aligned
-        assert a.flags.updateifcopy == b.flags.updateifcopy
+        if LooseVersion(np.__version__) >= LooseVersion("1.14.0"):
+            assert a.flags.writebackifcopy == b.flags.writebackifcopy
+        else:
+            assert a.flags.updateifcopy == b.flags.updateifcopy
         assert np.all(a == b)
         assert not b.flags.owndata
         assert b.base is base
@@ -282,17 +310,17 @@ def test_overload_resolution(msg):
             1. (arg0: numpy.ndarray[int32]) -> str
             2. (arg0: numpy.ndarray[float64]) -> str
 
-        Invoked with:"""
+        Invoked with: """
 
     with pytest.raises(TypeError) as excinfo:
         m.overloaded3(np.array([1], dtype='uintc'))
-    assert msg(excinfo.value) == expected_exc + " array([1], dtype=uint32)"
+    assert msg(excinfo.value) == expected_exc + repr(np.array([1], dtype='uint32'))
     with pytest.raises(TypeError) as excinfo:
         m.overloaded3(np.array([1], dtype='float32'))
-    assert msg(excinfo.value) == expected_exc + " array([ 1.], dtype=float32)"
+    assert msg(excinfo.value) == expected_exc + repr(np.array([1.], dtype='float32'))
     with pytest.raises(TypeError) as excinfo:
         m.overloaded3(np.array([1], dtype='complex'))
-    assert msg(excinfo.value) == expected_exc + " array([ 1.+0.j])"
+    assert msg(excinfo.value) == expected_exc + repr(np.array([1. + 0.j]))
 
     # Exact matches:
     assert m.overloaded4(np.array([1], dtype='double')) == 'double'
@@ -400,3 +428,20 @@ def test_array_create_and_resize(msg):
     a = m.create_and_resize(2)
     assert(a.size == 4)
     assert(np.all(a == 42.))
+
+
+@pytest.unsupported_on_py2
+def test_index_using_ellipsis():
+    a = m.index_using_ellipsis(np.zeros((5, 6, 7)))
+    assert a.shape == (6,)
+
+
+@pytest.unsupported_on_pypy
+def test_dtype_refcount_leak():
+    from sys import getrefcount
+    dtype = np.dtype(np.float_)
+    a = np.array([1], dtype=dtype)
+    before = getrefcount(dtype)
+    m.ndim(a)
+    after = getrefcount(dtype)
+    assert after == before