t/ffi_build.t: Failing on some FreeBSD testers

[jkeenan]

When I run CPANtesters reporting on FFI-Platypus on FreeBSD-13, I consistently get failures in t/ffi_build.t -- even though other CPANtester rigs are passing on this platform.

Typical failure report:
http://www.cpantesters.org/cpan/report/ff162328-b74b-11ef-b545-ee31b6e4ddea
Run on perl-5.41.6 (but has also failed on perl-5.38.0, 5.40.0, 5.41.4)

Typical failure:

    t/00_diag.t .............................. ok
        # Failed test 'no error'
        # at t/ffi_build.t line 145.
        # +c++ -DPIC -fPIC -DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -DNO_POSIX_2008_LOCALE -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -O2 -pipe -fstack-protector -fno-strict-aliasing -I/usr/home/jkeenan/.cpan/build/FFI-Platypus-2.09-0/blib/lib/auto/share/dist/FFI-Platypus/include -c corpus/ffi_build/project-cxx/foo1.cxx -o corpus/ffi_build/project-cxx/tmpbuild.55419.1733872234/foo1.o
        # +c++ -DPIC -fPIC -DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -DNO_POSIX_2008_LOCALE -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -O2 -pipe -fstack-protector -fno-strict-aliasing -I/usr/home/jkeenan/.cpan/build/FFI-Platypus-2.09-0/blib/lib/auto/share/dist/FFI-Platypus/include -c corpus/ffi_build/project-cxx/foo2.cpp -o corpus/ffi_build/project-cxx/tmpbuild.55419.1733872234/foo2.o
        # In file included from corpus/ffi_build/project-cxx/foo2.cpp:3:
        # In file included from /usr/include/c++/v1/iostream:43:
        # In file included from /usr/include/c++/v1/ios:222:
        # In file included from /usr/include/c++/v1/__locale:15:
        # In file included from /usr/include/c++/v1/__memory/shared_ptr.h:27:
        # In file included from /usr/include/c++/v1/__memory/compressed_pair.h:14:
        # /usr/include/c++/v1/__fwd/get.h:18:10: fatal error: '__tuple/tuple_element.h' file not found
        #    18 | #include <__tuple/tuple_element.h>
        #       |          ^~~~~~~~~~~~~~~~~~~~~~~~~
        # 1 error generated.

    # Failed test 'build c++'
    # at t/ffi_build.t line 196.
    t/ffi_build.t ............................ 
    Dubious, test returned 1 (wstat 256, 0x100)
    Failed 1/5 subtests 

If I am missing a prerequisite (tuple_element.h), please either tell me how to satisfy that pre-req or revise the library to require it.