Due to library conflicts, Fedora will have to put libiscsi in
/usr/lib/iscsi.  Simplify configuration by using a pkg-config
file.  The Fedora package will distribute one, and the patch
to add it has been sent to upstream libiscsi as well.

Cc: qemu-stable@nongnu.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>