fix build errors with sz_link and missing hdf5

[daeho-ro]

cd /private/tmp/kallisto-20260228-18650-dy0tkb/kallisto-0.52.0/ext/bifrost/build/src && /opt/homebrew/Library/Homebrew/shims/mac/super/clang++ -DMAX_GMER_SIZE=32 -DMAX_KMER_SIZE=32 -I/private/tmp/kallisto-20260228-18650-dy0tkb/kallisto-0.52.0/ext/bifrost/src -Wno-subobject-linkage -Wno-return-type -std=c++11  -O3 -DNDEBUG -arch arm64 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX15.sdk -O3 -MD -MT src/CMakeFiles/bifrost_static.dir/Bifrost.cpp.o -MF CMakeFiles/bifrost_static.dir/Bifrost.cpp.o.d -o CMakeFiles/bifrost_static.dir/Bifrost.cpp.o -c /private/tmp/kallisto-20260228-18650-dy0tkb/kallisto-0.52.0/ext/bifrost/src/Bifrost.cpp
In file included from /private/tmp/kallisto-20260228-18650-dy0tkb/kallisto-0.52.0/ext/bifrost/src/Bifrost.cpp:2:
In file included from /private/tmp/kallisto-20260228-18650-dy0tkb/kallisto-0.52.0/ext/bifrost/src/ColoredCDBG.hpp:10:
In file included from /private/tmp/kallisto-20260228-18650-dy0tkb/kallisto-0.52.0/ext/bifrost/src/DataManager.hpp:10:
/private/tmp/kallisto-20260228-18650-dy0tkb/kallisto-0.52.0/ext/bifrost/src/DataStorage.tcc:81:69: error: no member named 'sz_link' in 'DataStorage<Unitig_data_t>'
   81 |         for (size_t i = 0; i != sz_link; ++i) unitig_cs_link[i] = o.sz_link[i].load();
      |                                                                   ~ ^
1 error generated.
make[5]: *** [src/CMakeFiles/bifrost_static.dir/Bifrost.cpp.o] Error 1

• Fix compilation error with custom unitig data pmelsted/bifrost#18

• Compiling with HDF5 libraries is broken in 0.52.0 #505