run clang tests from test-xtensor-clang to get name in CI test log

enables failure of xreducer.average test to be ignored if
MARK_FLAKEY_TEST is defined.

Used to enable i386 to build.

Mark test as "may_fail" rather than "skip" to enable the underlying
bug to be monitored.

manage low-memory arches using "-Os -g0"

manage mipsel by switching off -march=native
(cmake -Darch_native_supported=OFF)
-mxgot is not needed in that case.

Thanks YunQiang Su and Adrian Bunk for help resolving the mipsel build
problems.

remove -g build flag on low-memory arches (required for mipsel to
succeed, with or witout -O2 or -O0)

Closes: #995867.

That's amd64 only (and kfreebsd is untested).

Restrict in debian/tests also. arm64, i386 tests continue to fail
(Bugs #994246, #994248)

Doesn't help mipsel, and only makes the i386 build slow.

provides cmake option BUILD_TEST_XNPY to skip test_xnpy in tests.

Required to build s390x, hppa, powerpc, ppc64, sparc64.

Default BUILD_TEST_XNPY=ON for other arches.

See Bug#985699, and
https://github.com/xtensor-stack/xtensor/issues/2328

needed to avoid virtual memory exhausted.

Use together with --no-parallel.

to ensure build independent from network

updates sphinx API in conf.py to fix doc build with sphinx 4.2.

see https://github.com/xtensor-stack/xtensor/issues/2441
https://github.com/sphinx-doc/sphinx/issues/7747

instead of -O0 (to try to achieve a mipsel build)

mipsel problems raised upstream at
https://github.com/xtensor-stack/xtensor/issues/2440

finds packages after the test project has been set in
tests/CMakeFiles.txt when building tests only using installed packages
(debian/tests).

Otherwise there is the error
"FindThreads only works if either C or CXX language is enabled".

cf.
https://stackoverflow.com/questions/54349824/findthreads-only-works-if-either-c-or-cxx-language-is-enabled

debian patch doctest_PR2405.patch applies upstream PR2405 to convert
to doctest

refresh doctest_PR2405.patch to match

rename test_EXPECT_DOUBLE_EQ.patch to test_EXPECT_DOUBLE_EQ_PR2436.patch
to apply upstream PR#2436 (plus test_common_macros.hpp)

Uses EXPECT_DOUBLE_EQ (scalar_near) instead of EXPECT_EQ for tests
which failed in i386 builds.

same problem as i386, x32

/<<PKGBUILDDIR>>/include/xtensor/xassign.hpp:671:104: error: invalid use of incomplete type ‘xt::xfunction<xt::detail::plus, const xt::xarray_container<xt::uvector<long int, xsimd::aligned_allocator<long int, 16> >, xt::layout_type::row_major, xt::svector<unsigned int, 4, std::allocator<unsigned int>, true>, xt::xtensor_expression_tag>&, const xt::xarray_container<xt::uvector<long int, xsimd::aligned_allocator<long int, 16> >, xt::layout_type::row_major, xt::svector<unsigned int, 4, std::allocator<unsigned int>, true>, xt::xtensor_expression_tag>&>::simd_return_type<long int>’ {aka ‘class xsimd::batch<long int, 4>’}
  671 |             e1.template store_simd<lhs_align_mode>(i, e2.template load_simd<rhs_align_mode, value_type>(i));
      |                                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from /usr/include/xsimd/types/xsimd_base.hpp:26,
                 from /usr/include/xsimd/types/xsimd_traits.hpp:16,
                 from /usr/include/xsimd/xsimd.hpp:16,
                 from /<<PKGBUILDDIR>>/include/xtensor/xtensor_config.hpp:75,
                 from /<<PKGBUILDDIR>>/include/xtensor/xbuffer_adaptor.hpp:21,
                 from /<<PKGBUILDDIR>>/include/xtensor/xarray.hpp:19,
                 from /<<PKGBUILDDIR>>/test/test_extended_broadcast_view.cpp:16:
/usr/include/xsimd/types/xsimd_utils.hpp:26:11: note: declaration of ‘xt::xfunction<xt::detail::plus, const xt::xarray_container<xt::uvector<long int, xsimd::aligned_allocator<long int, 16> >, xt::layout_type::row_major, xt::svector<unsigned int, 4, std::allocator<unsigned int>, true>, xt::xtensor_expression_tag>&, const xt::xarray_container<xt::uvector<long int, xsimd::aligned_allocator<long int, 16> >, xt::layout_type::row_major, xt::svector<unsigned int, 4, std::allocator<unsigned int>, true>, xt::xtensor_expression_tag>&>::simd_return_type<long int>’ {aka ‘class xsimd::batch<long int, 4>’}
   26 |     class batch;
      |           ^~~~~

uses EXPECT_DOUBLE_EQ instead of EXPECT_EQ for tests which failed in
i386 builds.

Just patching the tests which gave an error, not all instances of
EXPECT_EQ.

See https://github.com/xtensor-stack/xtensor/issues/2435 for the
upstream Issue.

to try to avoid exhausting virtual memory

same error message as reported for i386

Bug#994248, with upstream xtensor Issue#2434, xsimd Issue#287.

See Bug#994246, with upstream xtensor Issue#2433, xsimd Issue#400.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=994246
https://github.com/xtensor-stack/xtensor/issues/2433
https://github.com/xtensor-stack/xsimd/issues/400

to ensure sphinx-build is available.

provides dot, used when building docs