Projects that use Pthreads-Win32 no longer compile with Visual Studio 2015 since timespec gets already defined in time.h. To avoid this error apply this patch to pthread.h. It inserts the following modification:

#if defined(_MSC_VER) && _MSC_VER >= 1900 && !defined(_CRT_NO_TIME_T)
#define _TIMESPEC_DEFINED
#endif

An example project can be found here: solution