tools/libxc: Provide evtchn_port_or_error_t for compat xenctrl interface

c/s 2d2f789 "tools: rename libxc's evtchn_port_or_error_t with an xc_
prefix" doesn't cater for older applications which have requested
XC_WANT_COMPAT_EVTCHN_API

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

tools/libxc/include/xenctrl_compat.h

@@ -51,6 +51,7 @@ void *xc_map_foreign_bulk(xc_interface *xch, uint32_t dom, int prot,
 #ifdef XC_WANT_COMPAT_EVTCHN_API
 
 typedef struct xenevtchn_handle xc_evtchn;
+typedef xc_evtchn_port_or_error_t evtchn_port_or_error_t;
 
 xc_evtchn *xc_evtchn_open(xentoollog_logger *logger,
                              unsigned open_flags);