Using %zu seems to break mingw :/
It looks like we found out why we weren't using %zu before:
17:55:39 In file included from src/or/or.h:72:0,
17:55:39 from src/or/circuitlist.c:54:
17:55:39 src/or/circuitlist.c: In function 'circuits_handle_oom':
17:55:39 src/or/circuitlist.c:2407:26: error: unknown conversion type character 'z' in format [-Werror=format=]
17:55:39 log_notice(LD_GENERAL, "We're low on memory (cell queues total alloc: %zu,"
17:55:39 ^
17:55:39 ./src/common/torlog.h:232:45: note: in definition of macro 'log_notice'
17:55:39 log_fn_(LOG_NOTICE, domain, __FUNCTION__, args, ##__VA_ARGS__)
17:55:39 ^~~~
17:55:39 src/or/circuitlist.c:2407:26: error: unknown conversion type character 'z' in format [-Werror=format=]
17:55:39 log_notice(LD_GENERAL, "We're low on memory (cell queues total alloc: %zu,"
17:55:39 ^In theory we can select a more c99 one with __USE_MINGW_ANSI_STDIO, but that would change our stdio everywhere. (Which is a little scary.)
We could also define a PRIsz macro that has the correct format for whatever compiler we are using. That might be a better choice.