rtld-elf: Remove x86 elf_rtld.x linker scripts.

First, amd64 version of the script cannot work at least due to the
wrong architecture specification. Second, kernel can activate shared
objects for long time, due to PIE support.

It seems the intent was to allow ld-elf.so.1 to be build and used as
an executable. Since we have direct exec mode implemented for dso
ld-elf.so.1, the non-functional and commented out scripts can be
finally removed.

Sponsored by: The FreeBSD Foundation
MFC after: 1 week