Visual Studio error with 'timespec' structure

Add this compiler flag:

-DHAVE_STRUCT_TIMESPEC

Despite this question is already answered correctly, there is also another way to solve this problem.

First, problem occurs because pthreads-win32 internally includes time.h which already declares timespec struct.

To avoid this error the only thing we should do is this:

#define HAVE_STRUCT_TIMESPEC
#include <pthread.h>