tools/oxenstored: Fix | vs & error in fd event handling

tools/oxenstored: Fix | vs & error in fd event handling

This makes fields 0 and 1 true more often than they should be, resulting
problems when handling events.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Dave Scott <Dave.Scott@eu.citrix.com>
CC: Zheng Li <zheng.li3@citrix.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: Zheng Li <dev@zheng.li>
Reviewed-by: David Scott <dave.scott@citrix.com>