On a RPI we can only fire 244 actors

[sphaero]

SPHACTOR_SOCKET_LIMIT=244 make check runs fine

But 245 freezes. Interrupting it gives a hint:

Running libsphactor selftests...
 * sphactor: I: 20-02-13 17:52:41 command: ENDPOINT
I: 20-02-13 17:52:41 command: UUID
I: 20-02-13 17:52:41 command: CONNECT
I: 20-02-13 17:52:41 command: DISCONNECT
I: 20-02-13 17:52:41 command: $TERM
I: 20-02-13 17:52:41 Hello2 actor 9367EB says: HELLO
I: 20-02-13 17:52:41 Hello actor 9B2C14 says: WORLD
I: 20-02-13 17:52:41 Hello2 actor 9367EB says: AND
I: 20-02-13 17:52:41 Hello actor 9B2C14 says: ALIEN
I: 20-02-13 17:52:41 Hello2 actor 9367EB says: SPACELINGS
^C^C^Csphactor_selftest: src/sphactor.c:176: sphactor_ask_connect: Assertion `endpoint' failed.
make[2]: *** [Makefile:1722: check-local] Aborted
make[1]: *** [Makefile:1514: check-am] Interrupt
make: *** [Makefile:1067: check-recursive] Interrupt