fix #2883, #2857 pipe fds leak when fork() failed on bg aof rw

src/aof.c

@@ -1295,6 +1295,7 @@ int rewriteAppendOnlyFileBackground(void) {
             serverLog(LL_WARNING,
                 "Can't rewrite append only file in background: fork: %s",
                 strerror(errno));
+            aofClosePipes();
             return C_ERR;
         }
         serverLog(LL_NOTICE,