A no-threads stdlib built at -O0 does not link: http_park_resume calls http_pool_submit_conn, which only threaded builds define #3121

What happens

A cooperative (no-threads) stdlib built at -O0 does not link the shared runtime:

make stdlib EXTRA_CFLAGS='-DAETHER_NO_THREADING -g -O0'
...
ld: build/libaether.a(aether_http_server.o): in function `http_park_resume':
std/net/aether_http_server.c:5491: undefined reference to `http_pool_submit_conn'
make: *** [Makefile:2014: build/shared/aether.dll] Error 1

Found on Windows (MinGW GCC 16.2), where the shared runtime is linked as part of make stdlib.

Why

std/net/aether_http_pool.c defines http_pool_submit_conn only under #if AETHER_HAS_THREADS && AETHER_HAS_NETWORKING. std/net/aether_http_server.c defines http_park_resume, which calls it, under no such guard. Only threaded paths reach http_park_resume. At -O2 the compiler drops the unused static function, and the reference goes with it. At -O0 the function and its reference stay, and the link fails.

Fix

Compile http_park_resume under the condition its only caller is compiled under (#if AETHER_HAS_THREADS, where the server creates its park lot), so the reference no longer depends on the optimizer.