Don't include pthread.h nor semaphore.h with MA_NO_DEVICE_IO.

Public issue https://github.com/dr-soft/miniaudio/issues/138

miniaudio.h

@@ -1456,8 +1456,12 @@ extern "C" {
     #endif
 #else
     #define MA_POSIX
+
+    /* We only use multi-threading with the device IO API, so no need to include these headers otherwise. */
+#if !defined(MA_NO_DEVICE_IO)
     #include <pthread.h>    /* Unfortunate #include, but needed for pthread_t, pthread_mutex_t and pthread_cond_t types. */
     #include <semaphore.h>
+#endif
 
     #ifdef __unix__
         #define MA_UNIX

tests/test_generation/ma_test_generation.c

+#define MA_NO_DEVICE_IO
 #include "../test_common/ma_test_common.c"
 
 #include "ma_test_generation_noise.c"