BUG/MINOR: startup: certain goto paths in init_pollers fail to free

If we fail to initialize pollers due to fdtab/fdinfo/polled_mask
not getting allocated, we free any of those that were allocated
and exit. However the ordering was incorrect, and there was an old
unused and unreachable "fail_cache" path as well, which needs to
be taken when no poller works.

This was introduced with this commit during 1.9-dev :
   cb92f5c ("MINOR: pollers: move polled_mask outside of struct fdtab.")

It needs to be backported to 1.9 only.

src/fd.c

@@ -528,6 +528,7 @@ int init_pollers()
 
 	if ((polled_mask = calloc(global.maxsock, sizeof(unsigned long))) == NULL)
 		goto fail_polledmask;
+
 	if ((fdinfo = calloc(global.maxsock, sizeof(struct fdinfo))) == NULL)
 		goto fail_info;
 
@@ -557,15 +558,13 @@ int init_pollers()
 			return 1;
 		}
 	} while (!bp || bp->pref == 0);
-	return 0;
 
- fail_cache:
 	free(fdinfo);
  fail_info:
-	free(fdtab);
- fail_tab:
 	free(polled_mask);
  fail_polledmask:
+	free(fdtab);
+ fail_tab:
 	return 0;
 }