Something similar was previously done in 07cc71b8 from a Debian
patch, and eventually reverted; it redefined the ast atomic
functions asoincint() and asodecint() to be gcc-specific. This
imports the upstream version from the ksh 93v- beta instead.
This commit is based on an OpenSUSE patch:
https://build.opensuse.org/package/view_file/shells/ksh/ksh93-joblock.dif
src/cmd/ksh93/include/jobs.h:
- Replace job locking mechanism with the 93v- version which uses
the atomic libast functions asoincint(), asogetint() and
asodecint(). See: src/lib/libast/man/aso.3
src/cmd/ksh93/sh/jobs.c: job_subsave():
- Revert gcc optimiser bug workaround from c258a04f.
It should now be unnecessary.