Fix more warnings

src/openrct2-ui/drawing/engines/opengl/OpenGLDrawingEngine.cpp

@@ -18,7 +18,7 @@
 
 #include <unordered_map>
 #include <vector>
-#include <SDL_platform.h>
+#include <SDL.h>
 
 #include <openrct2/config/Config.h>
 #include <openrct2/core/Console.hpp>

src/openrct2/audio/AudioMixer.cpp

@@ -28,8 +28,6 @@ extern "C"
     #include "../rct2.h"
 }
 
-#define SDL_MIX_MAXVOLUME 128
-
 using namespace OpenRCT2;
 using namespace OpenRCT2::Audio;
 

src/openrct2/audio/AudioMixer.h

@@ -18,6 +18,8 @@
 
 #include "../common.h"
 
+#define SDL_MIX_MAXVOLUME 128
+
 #define MIXER_LOOP_NONE         0
 #define MIXER_LOOP_INFINITE     -1
 

src/openrct2/common.h

@@ -31,6 +31,7 @@
 #include <assert.h>
 #include <limits.h>
 #include <math.h>
+#include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>

src/openrct2/localisation/localisation.c

@@ -16,6 +16,8 @@
 
 #include "../common.h"
 
+#include <ctype.h>
+
 #ifdef __WINDOWS__
 #include <windows.h>
 #else