AbortController and AbortSignal lowered to fetch.abort* entry points, so
a program that only used them linked the fetch unit with its socket,
HTTP, TLS and zlib dependencies. They now lower to the abort.* entry
points on every target, a new abortSignal feature links scr_abort.c (the
fetch unit's signal implementation built without its transport, which
WASI already ships) and the EventTarget unit, and programs that also
fetch keep the fetch unit's copy.
Chris Tate
e84d332264