Fix conditional export of kvh.h and a.out.h to userspace.

Some architectures have moved the asm/ into arch/ and some have not.
This patch checks for a.out.h and kvh.h in both places before exporting
the corresponding file from linux/

[dwmw2: simplified a little]
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>