So, I'm going to make one more MI change in ld.elf_so, that will
impact x86_64.

Basically, I'm going to eliminate the vestiges of
-DRTLD_RELOCATE_SELF.  This means that the flag itself, and all the
`dodebug' arguments passed down to various functions, will all go
away.

All platforms will be expected to prebind ld.elf_so before calling
main().  I have already adjust 6 platforms to do this right; the only
that does not is x86_64.  Fixing it is essentially a matter of copying
20 lines of code from one of the other mdreloc.c implementations, and
adding a stub to call the self-relocate function.

The upside of this change is that ld.elf_so will be smaller and
slightly faster.  Also LD_DEBUG will work correctly on all platforms.

Any further questions may be directed to me.