golang/xenlight: Fixing compilation for go 1.11

This deals with two casting issues for compiling under go 1.11:
- explicitly cast to *C.xentoollog_logger for Ctx.logger pointer
- add cast to unsafe.Pointer for the C string cpath

Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>

tools/golang/xenlight/xenlight.go

@@ -854,7 +854,7 @@ func (Ctx *Context) Open() (err error) {
 	}
 
 	ret := C.libxl_ctx_alloc(&Ctx.ctx, C.LIBXL_VERSION,
-		0, unsafe.Pointer(Ctx.logger))
+		0, (*C.xentoollog_logger)(unsafe.Pointer(Ctx.logger)))
 
 	if ret != 0 {
 		err = Error(-ret)
@@ -869,7 +869,7 @@ func (Ctx *Context) Close() (err error) {
 	if ret != 0 {
 		err = Error(-ret)
 	}
-	C.xtl_logger_destroy(unsafe.Pointer(Ctx.logger))
+	C.xtl_logger_destroy((*C.xentoollog_logger)(unsafe.Pointer(Ctx.logger)))
 	return
 }
 
@@ -1170,7 +1170,7 @@ func (Ctx *Context) ConsoleGetTty(id Domid, consNum int, conType ConsoleType) (p
 		err = Error(-ret)
 		return
 	}
-	defer C.free(cpath)
+	defer C.free(unsafe.Pointer(cpath))
 
 	path = C.GoString(cpath)
 	return
@@ -1190,7 +1190,7 @@ func (Ctx *Context) PrimaryConsoleGetTty(domid uint32) (path string, err error)
 		err = Error(-ret)
 		return
 	}
-	defer C.free(cpath)
+	defer C.free(unsafe.Pointer(cpath))
 
 	path = C.GoString(cpath)
 	return