don't include os_compat.h

When there are standardized headers, use these instead of the bloated
os_compat.h.

src/decoder_control.c

@@ -18,6 +18,8 @@
 
 #include "decoder_control.h"
 
+#include <assert.h>
+
 struct decoder_control dc;
 
 void dc_init(void)