OpenBSD does not implement pthread_setname_np

Index: desmume/src/libretro-common/rthreads/rthreads.c
--- desmume/src/libretro-common/rthreads/rthreads.c.orig
+++ desmume/src/libretro-common/rthreads/rthreads.c
@@ -54,6 +54,7 @@
 #include <sys/sys_time.h>
 #else
 #include <pthread.h>
+#include <pthread_np.h>
 #include <time.h>
 #endif
 
@@ -323,7 +324,7 @@ void sthread_setname(sthread_t *thread, const char *na
    // any thread. At the time of this writing (2021/08/30), there is no way to
    // set the thread name from a different thread when running an Apple OS.
 #if !defined(USE_WIN32_THREADS) && !defined(__APPLE__)
-   pthread_setname_np(thread->id, name);
+   pthread_set_name_np(thread->id, name);
 #endif
 }
 
