miniupnpd ipq40xx odd behaviour however enabling log_output works

@neheb #
I have a issue with miniupnpd, have tested both OpenWrt 18x to 21.02.0-rc1 r16046-59980f7aaf via ipq40xx / ARMv7 target

When first restarted miniupnpd it doesn't seems to work or opening any ports for any of my Consoles such as PS4 and Xbox One X however it gives messages like so:

Fri May 14 09:19:28 2021 daemon.notice miniupnpd[8632]: HTTP listening on port 5000
Fri May 14 09:19:28 2021 daemon.warn miniupnpd[8632]: no HTTP IPv6 address, disabling IPv6
Fri May 14 09:19:28 2021 daemon.notice miniupnpd[8632]: Listening for NAT-PMP/PCP traffic on port 5351

However if i enable the debug mode "option log_output '1'" and restart miniupnpd it works without issue,

Fri May 14 17:17:47 2021 daemon.info miniupnpd[12908]: HTTP REQUEST from [::ffff:192.168.170.252]:52130 : GET /rootDesc.xml (HTTP/1.1)
Fri May 14 17:17:47 2021 daemon.info miniupnpd[12908]: HTTP REQUEST from [::ffff:192.168.170.252]:49981 : POST /ctl/IPConn (HTTP/1.1)
Fri May 14 17:17:47 2021 daemon.info miniupnpd[12908]: AddPortMapping: ext port 3074 to 192.168.170.252:3074 protocol UDP for: DemonwarePortMapping leaseduration=604800 rhost=
Fri May 14 17:17:47 2021 daemon.info miniupnpd[12908]: updating existing port mapping 3074 UDP (rhost '') => 192.168.170.252:3074

No idea if it affects any other targets but for the fritzbox 7530 ipq40xx / ARM Cortex A7 neon-vfpv4 its one of them. Not tired the new miniupnpd-igdv1_2.2.1-2_arm_cortex-a7_neon-vfpv4.ipk yet in the development snapshots https://downloads.openwrt.org/snapshots/packages/arm_cortex-a7_neon-vfpv4/packages/miniupnpd-igdv1_2.2.1-2_arm_cortex-a7_neon-vfpv4.ipk but will test with another release of the next 21.02.0-rc2 or so when it arrives but if you can look at this startup odd behaviour issue ill be grateful

@neheb

Reproduce the startup behavior on the reported ipq40xx/ARMv7 setup, comparing miniupnpd restarts with and without option log_output '1'. Start from the miniupnpd package configuration and the provided startup and port-mapping logs; done means identifying why logging changes behavior and confirming a fix that allows mappings without debug logging.