O_NONBLOCK broken on darwin and irix?

i’ve been dealing with a mysql bug on irix and mac os x that turned up in our test suite once i fixed the kill test to actually do the test properly. after much digging in code and staring at debug traces, i noticed on irix that in the thread that is being killed, it was stuck in a blocking read that the calling code believed would be non-blocking.

by changing our setting of the non-blocking mode to use both O_NDELAY and O_NONBLOCK instead of just O_NONBLOCK, i was able to get the code to work. but i’m not sure why it is necessary.

on the bright side, this may also fix this bug about wait_timeout not working on mac os x.