pkg/lwip: Add thread safety check when using DEVELHELP

[yarrick]

Contribution description

When DEVELHELP is enabled, add checks that unprotected lwip functions are called correctly:

• Not be called from interrupts.
• If called from outside the tcpip thread, the lock must be held

The check is a macro to preserve the file/line of where it fired, to simplify debugging.

Adds locking to some calls in sock implementation to make it safe.
Having this enabled will make it harder to add new unsafe code.

Netif handling has already been made safe in the switch to netifapi functions for dhcp and netif link up/down.

Testing procedure

All lwip tests still work.

When calling dhcp_start instead of netifapi version in pkg/lwip/contrib/lwip.c, the following failure occurs (when IPv4 enabled) on native:
Assertion "Core lock held" failed at [...]/RIOT/build/pkg/lwip/src/core/ipv4/dhcp.c:742

Sending data with lwip sock still works when manually using test commands on tests/lwip

Issues/PRs references

None

[yarrick]

Still looking for a review of this.

[miri64]

Still looking for a review of this.

Sorry, was very busy the last few month. I will have a look ASAP!

[miri64]

The doc says LWIP_TCPIP_CORE_LOCKING needs to be set to 1 for this feature to be used. So wouldn't it be more sensible to make the #ifdef DEVELHELPs #if IS_ACTIVE(LWIP_TCPIP_CORE_LOCKING) instead and set LWIP_TCPIP_CORE_LOCKING == 1 when DEVELHELP is defined in lwipopts.h?

[miri64]

ACK. I ran tests/lwip on native. The remaining tests should run on Murdock.

[miri64]

Please squash

[fjmolinas]

I bisected the failing test on native(#17115 (comment)), I'm not sure if this PIR is to blame or if starting from this PR we have the mechanism to identify the underlying issue.