adds specialization of write_vector_with_single_rank

This should fix the undefined reference error below.

CMakeFiles/NSVE_self_consistent.dir/NSVE_self_consistent.cpp.o: In function `NSVE_self_consistent<float>::do_stats()':
/home/tobae/repos/turtle_resize_with_stokes/test/TurTLE_build_NSVE_self_consistent-single-v4.3.post1+g5b6c76d0.dirty/NSVE_self_consistent.cpp:1326: undefined reference to `int hdf5_tools::write_vector_with_single_rank<long long>(std::vector<long long, std::allocator<long long> >, long, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)'

@toba: please confirm that it does fix the problem for gcc 7 (I cannot reproduce it with my gcc 11). If yes, merge, otherwise please post error message here.

cpp/hdf5_tools.cpp

@@ -552,6 +552,12 @@ int hdf5_tools::write_vector_with_single_rank(
         const hid_t group,
         const std::string dset_name);
 
+template
+int hdf5_tools::write_vector_with_single_rank(
+        const std::vector<long long int> v,
+        const hid_t group,
+        const std::string dset_name);
+
 template
 int hdf5_tools::gather_and_write_with_single_rank<double>(
         const int myrank,