tp: Make the header file compilable on Windows
MSVC does not support pthread. For this reason, we needed to
include the compatibility header in monkey, not <pthread.h>.
This patch fixes it thusly.
#define FLB_THREAD_POOL_STOPPED 2
#include <fluent-bit/flb_info.h>
+#ifdef FLB_SYSTEM_WINDOWS
+#include <monkey/mk_core/external/winpthreads.h>
+#else
#include <pthread.h>
+#endif
struct worker_params {
void (*func) (void *);
