ln -s perl64_mhdrg.so libmhdrg.so

   perl -MDynaLoader -I . -e 'package mhdrg; use parent "DynaLoader"; bootstrap mhdrg; package main; mhdrg("f22", "/usr/tmp/drgmasks","1","34","2","V3000","    ","5","4");'

   perl: symbol lookup error: ./libmhdrg.so: undefined symbol: Perl_Tstack_sp_ptr