thrpool: remove stack size changing for all platforms
As compilers and system C libraries change, the using a
non-default stack size is too risky and can lead to
difficult-to-diagnose problems.
Using the default stack size seems to solve the segfaults
at http_close reported by Xiao Yu <xyu@automattic.com>.
Users on modern 64-bit systems were unlikely to find any benefit
in using a small stack size with this code base.
Users on 32-bit systems who wish to continue with a minimal
stack should use "ulimit -s" in startup scripts or configure
their process manager appropriately (e.g. setting the
"LimitSTACK" directive in described in systemd.exec(5)).
Reported-and-tested-by: Xiao Yu <xyu@automattic.com>
Link: https://yhbt.net/cmogstored-public/CABfxMcW+kb5gwq3pSB_89P49EVv+4UkJXz+mUPQTy19AdrwbAg@mail.gmail.com/T/