Replace all use of ERR_add_error_data with ERR_asprintf_error_data.
This avoids a lot of ugly gymnastics to do snprintfs before sending the
bag of strings to ERR, and eliminates at least one place in dso_dlfctn.c
where it was being called with the incorrect number of arguments and
using random things off the stack as addresses of strings.
ok krw@, jsing@