ffmpeg-mux: Disable stdout/stderr on Windows

These server no purpose unless the ENABLE_FFMPEG_MUX_DEBUG flag is
enabled, and will ultimately just cause problems.

plugins/obs-ffmpeg/ffmpeg-mux/ffmpeg-mux.c

@@ -47,6 +47,13 @@
 
 #define AVIO_BUFFER_SIZE 65536
 
+#if defined(_WIN32) && !defined(ENABLE_FFMPEG_MUX_DEBUG)
+#define fprintf(...)
+#define printf(...)
+#define fflush(x)
+#define puts(x)
+#endif
+
 /* ------------------------------------------------------------------------- */
 
 static char *global_stream_key = "";