Last dso_dlfcn.c check-in said "Use Dl_info only on systems where it is

known to exist. It does not exist on AIX 4.3.3, AIX 5.1, SCO 5, or Cygwin"
and disabled it on banch of systems it's known to exists, such as FreeBSD,
Solaris, 64-bit HP-UX, MacOS X. Get it straight.