Since the child pipe was made non-blocking in r65993, it became possible to
write to child process without deadlocking when the pipe became full. However
this still resulted in an error from wxFileOutputStream as it didn't handle
EAGAIN returned from write() any differently than any other error, even though
it is an expected situation in this particular case.
Change Unix wxExecute() to use wxPipeOutputStream which ignores EAGAIN unlike
wxFileOutputStream to fix this.
See #12636.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66152 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Simply extract part of the code from evtloopunix.cpp into a reusable
wxPipe::MakeNonBlocking() function to be able to reuse it elsewhere.
See #12636.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@65992 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
