I guess what I mean to say here is: the hack of changing the VMA of a
shared library and modifying all the base-relative relocations will
work fine -- you're basically emulating what would happen if your
linker script set the address differently.  It's already fully
supported for shared libraries, and (with a recent bug fix to the
kernel) for ld.elf_so as well.

But, it doesn't really solve the `prebinding' problem.