fix(process): handle poll() interrupted by a signal (#38024)

It is indeed possible that a signal may arrive during flush_stream()
(e.g. SIGCHLD from another child process), so poll() again on EINTR.

Fixes the following Coverity warning:
_____________________________________________________________________________________________
*** CID 644345:         Error handling issues  (CHECKED_RETURN)
/src/nvim/event/proc.c: 405             in flush_stream()
399
400     #ifdef __linux__
401         // On Linux, libuv's polling (which uses epoll) doesn't flush PTY master's pending
402         // work on kernel workqueue, so use an explcit poll() before that. #37982
403         if (proc->type == kProcTypePty && !stream->did_eof) {
404           struct pollfd pollfd = { .fd = ((PtyProc *)proc)->tty_fd, .events = POLLIN };
>>>     CID 644345:         Error handling issues  (CHECKED_RETURN)
>>>     Calling "poll(&pollfd, 1UL, 0)" without checking return value. This library function may fail and return an error code.
405           poll(&pollfd, 1, 0);
406         }
407     #endif
408         // Poll for data and process the generated events.
409         loop_poll_events(proc->loop, 0);
410         if (stream->s.events) {

Another possible error is ENOMEM, which is probably not worth handling.
For reference, #23308 previously removed a case of ENOMEM handling, and
this PR also removes an outdated mention of that.

Also reduce the number of #ifdefs in non-OS-specific files.

0 files changed, 0 insertions, 0 deletions