rtld: Sync 1/7 - Handle premature symlook_obj call

rtld: Sync 1/7 - Handle premature symlook_obj call

It doesn't appear that this code is needed for x86 platforms as this
case should already be caught in early code, but it doesn't hurt
DragonFly to handle every possible case.

  Work around a situation where symlook_obj() could be called for the
  object for which digest_dynamic1() was not done yet.  Just return
  EINVAL and do not try to dereference NULL buckets hash array.

  This seems to happen on ia64 for rtld object itself where the
  R_IA_64_FPTR64LSB relocations require symbol lookup.  The dynamic
  linker itself does not rely on identity of the C-level function
  pointers (i.e. function descriptors).

Taken verbatim from:
FreeBSD SVN 235054 (05 MAY 2012)