Fix new cmake
Requiring MBsysC MR595.
- Fix return value of accelred symbolic function;
- Fix wrong OS detection in User IO
- Fix missing function to synchronize outputs in User IO
- Update loading function in main
- Store mbsysC installation directory in MbsData in main. This allow MBsysC to find the realtime process to be run, but the path is hardcoded (not portable).