In the linkers, collect objects in section "openbsd.mutable" and place

In the linkers, collect objects in section "openbsd.mutable" and place
them into a page-aligned region in the bss, with the right markers for
kernel/ld.so to identify the region and skip making it immutable.
While here, fix readelf/objdump versions to show all of this.
ok miod kettenis