Remove majority of warnings

There were a *lot* of warnings, managed to remove most of them.

Also, put warning flags before C_FLAGS and CXX_FLAGS, rather than after,
as -Wall -Wextra was overwriting flags that came before it.

libobs/media-io/audio-io.h

@@ -17,6 +17,7 @@
 
 #pragma once
 
+#include "media-io-defs.h"
 #include "../util/c99defs.h"
 
 #ifdef __cplusplus
@@ -28,8 +29,6 @@ extern "C" {
  * for the media.
  */
 
-#define MAX_AUDIO_PLANES 8
-
 struct audio_output;
 struct audio_line;
 typedef struct audio_output *audio_t;
@@ -64,7 +63,7 @@ enum speaker_layout {
 };
 
 struct audio_data {
-	const uint8_t       *data[MAX_AUDIO_PLANES];
+	const uint8_t       *data[MAX_AV_PLANES];
 	uint32_t            frames;
 	uint64_t            timestamp;
 	float               volume;