to avoid build error due to conflicting declaration:
flow/Profiler.actor.cpp: In function 'uint64_t gettid()':
flow/Profiler.actor.cpp:56:17: error: ambiguating new declaration of 'uint64_t gettid()'
FILE* f;
^
In file included from /nix/store/4wy9j24psf9ny4di3anjs7yk2fvfb0gq-glibc-2.31-dev/include/unistd.h:1170:0,
from ./flow/Platform.h:49,
from ./flow/flow.h:40,
from flow/Profiler.actor.cpp:39:
/nix/store/4wy9j24psf9ny4di3anjs7yk2fvfb0gq-glibc-2.31-dev/include/bits/unistd_ext.h:34:16: note: old declaration '__pid_t gettid()'
extern __pid_t gettid (void) __THROW;
^~~~~~
450de176cf