Add --kerneldir configure argument

This allows a user to override the default search path and also makes cross
compilation work a bit nicer wrt KVM detection.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5628 c046a42c-6fe2-441c-8c8c-71466251a162