improves error message for yac_alltoallv routine

src/core/dist_grid.c

src/core/interp_method_callback.c

src/core/interp_method_creep.c

src/core/interp_method_file.c

src/core/interp_method_spmap.c

src/core/interp_weights.c

src/core/yac_mpi.c

src/core/yac_mpi_internal.h

src/utils/duplicate_stencils.c

src/utils/read_scrip_grid.c