Following commit upstream removed the definition for elfobjdir in
favour of elf-objpfx. Adjust rtkaio to build with this.
commit 4134b50d6789c333707b1861a32314805bd0de5e
Author: Joseph Myers <joseph@codesourcery.com>
Date: Wed May 21 16:52:08 2014 +0000
Consistently use $(elf-objpfx).
As previously noted
<https://sourceware.org/ml/libc-alpha/2013-05/msg00696.html>,
$(elf-objpfx) and $(elfobjdir) are redundant and should be
consolidated. This patch consolidates on $(elf-objpfx) (for
consistency with $(csu-objpfx)), also changing direct uses of
$(common-objpfx)elf/ to use $(elf-objpfx).
