BUG/MINOR: spoe: Fix memory leak if failing to allocate memory

Technically harmless, but it annoys clang analyzer.

This bug was introduced in 336d3ef0e7.
This fix should be backported to HAProxy 1.9+.

src/flt_spoe.c

@@ -3751,6 +3751,7 @@ cfg_parse_spoe_agent(const char *file, int linenum, char **args, int kwm)
 				goto out;
 			}
 			if ((vph->name  = strdup(args[cur_arg])) == NULL) {
+				free(vph);
 				ha_alert("parsing [%s:%d] : out of memory.\n", file, linenum);
 				err_code |= ERR_ALERT | ERR_ABORT;
 				goto out;