* setting threadname is now done in a seperate function
* if setting the threadname fails, it just prints a warning now
instead of terminating the game with a FatalError
* setting threadname is now done in a seperate function so it's a bit
cleaner (it's different for every platform..)
* replace/refactor signaling code (based on my SDL threading branch and
the old pthread signaling code from RB):
- The interface is like on win32 now (Sys_Signal* functions instead of
overwriting idSysSignal class)
- created a custom signalHandle_t struct for that, which contains all
needed information
- Mimic Windows functions used in win32 implementation more closely,
e.g. signal all waiting threads on manualReset signalRaise, count
waiting threads etc. I'm pretty sure the behavior on Win32 and POSIX
now is identical (as far as possible).
* idSysSignal::Wait should now handle timeouts > 1s better (or at all)
* Use clock_gettime for Sys_Milliseconds()
* Use CLOCK_MONOTONIC_RAW (and CLOCK_MONOTONIC as fallback if
that's not available) for Sys_Milliseconds() and Sys_Microseconds()
CLOCK_MONOTONIC can behave strange when NTP is used
* Small fixes in Sys_Microseconds(): use 64bit int to store time
(like return type...), divide by 1000 (not 1000000) for nsec=>musec
