hdf5_ep

Fix a bug in H5D__virtual_write_one to stop an assertion from failing
deep in H5Dwrite---project the *clipped* virtual selection instead of
the virtual selection:

assertion "((src_space)->select.num_elem) == ((dst_space)->select.num_elem)"
failed: file "../../../vchoi_fork/src/H5Sselect.c", line 2617, function
"H5S_select_project_intersection"

with this backtrace:

    at /home/dyoung/plain-nbsd/src/lib/libc/gen/raise.c:48
    at /home/dyoung/plain-nbsd/src/lib/libc/stdlib/abort.c:74
    file=0xae9e3e80 "../../../vchoi_fork/src/H5Sselect.c", line=2617,
    function=0xae9e4ca0 <__func__.15686> "H5S_select_project_intersection",
    failedexpr=0xae9e0e54 "((src_space)->select.num_elem) ==
((dst_space)->select.num_elem)") at
/home/dyoung/plain-nbsd/src/lib/libc/gen/assert.c:72
    dst_space=0xae26f0dc, src_intersect_space=0xae0b577c,
    new_space_ptr=0xbfb85fac, share_selection=true)
    at ../../../vchoi_fork/src/H5Sselect.c:2749
    type_info=type_info@entry=0xbfb86084,
    file_space=file_space@entry=0xae0b577c, source_dset=0xae24741c,
    io_info=<optimized out>) at ../../../vchoi_fork/src/H5Dvirtual.c:2784
    type_info=0xbfb86084, nelmts=256, file_space=0xae0b577c,
    mem_space=0xae26ec8c, fm=0xadf0401c)
    at ../../../vchoi_fork/src/H5Dvirtual.c:2873
    mem_type_id=216172782113783837, mem_space=0xae26ec8c,
    file_space=0xae0b577c, buf=0xae203808)
    at ../../../vchoi_fork/src/H5Dio.c:780
    mem_type_id=216172782113783837, mem_space_id=288230376151711754,
    file_space_id=288230376151711755, dxpl_id=792633534417207304,
    buf=0xae203808, req=0x0)
    at ../../../vchoi_fork/src/H5VLnative_dataset.c:206
    mem_type_id=216172782113783837, mem_space_id=288230376151711754,
    file_space_id=288230376151711755, dxpl_id=792633534417207304,
    buf=0xae203808, req=0x0, cls=<optimized out>)
    at ../../../vchoi_fork/src/H5VLcallback.c:2152
    mem_type_id=216172782113783837, mem_space_id=288230376151711754,
    file_space_id=288230376151711755, dxpl_id=792633534417207304,
    buf=0xae203808, req=0x0) at ../../../vchoi_fork/src/H5VLcallback.c:2186
    mem_type_id=216172782113783837, mem_space_id=288230376151711754,
    file_space_id=288230376151711755, dxpl_id=792633534417207304,
    buf=0xae203808) at ../../../vchoi_fork/src/H5Dio.c:313