Sometimes Hang at Startup

[GenyMobile]

Sometimes a VM just hang at startup and is stuck forever.

We tracked it down to rtSchedRunThread() into 'src/VBox/Runtime/r3/linux/sched-linux.cpp' where it loops without end.

According to the pthreads documentation:

1. « pthreads functions do not set errno »
2. « the function can never fail with the error EINTR »

Which means if something happen to have set errno to EINTR before these lines, there no hope of escape. Moreover, checking for EINTR is useless.

The foloowing patch fixes this problem. As this file barely changed in 5.0 it also applies cleanly on this series.