Fix wrong forward declares (struct/class)

Requires removing the now-matching symbols from jsystem_stubs.cpp

include/d/actor/d_a_b_yo.h

@@ -8,7 +8,7 @@
 #include "d/d_bg_s_acch.h"
 
 class dBgW;
-class msg_class;
+struct msg_class;
 
 /**
  * @ingroup actors-enemies

include/d/d_event_data.h

@@ -4,7 +4,7 @@
 #include "global.h"
 #include "f_pc/f_pc_base.h"
 
-class msg_class;
+struct msg_class;
 
 struct event_binary_data_header {
     /* 0x00 */ u32 eventTop;  // offset to Event chunk

include/d/d_jcam_editor.h

@@ -6,7 +6,7 @@
 #include "JSystem/JUtility/JUTResFont.h"
 #include "JSystem/JKernel/JKRExpHeap.h"
 
-class JUTGamePad;
+struct JUTGamePad;
 
 class dJcame_c {
 public:

include/d/d_jpreviewer.h

@@ -10,7 +10,7 @@ namespace JStudio {
 
 class J2DOrthoGraph;
 class JKRExpHeap;
-class JUTGamePad;
+struct JUTGamePad;
 class JUTResFont;
 class tParse_;
 

include/d/d_kankyo.h

@@ -12,7 +12,7 @@
 
 class JPABaseEmitter;
 class cBgS_PolyInfo;
-class color_RGB_class;
+struct color_RGB_class;
 
 struct LIGHT_INFLUENCE {
     /* 0x00 */ cXyz mPosition;
@@ -148,12 +148,12 @@ struct LightStatus {
 };  // Size: 0xE8
 
 class fopAc_ac_c;
-class dKyd_lightSchejule;
-class stage_palette_info_class;
-class stage_pselect_info_class;
-class stage_envr_info_class;
-class stage_vrboxcol_info_class;
-class stage_plight_info_class;
+struct dKyd_lightSchejule;
+struct stage_palette_info_class;
+struct stage_pselect_info_class;
+struct stage_envr_info_class;
+struct stage_vrboxcol_info_class;
+struct stage_plight_info_class;
 class kytag08_class;
 
 struct dKy_pol_arg_struct {

include/d/d_kankyo_wether.h

@@ -5,7 +5,7 @@
 #include "SSystem/SComponent/c_sxyz.h"
 #include "SSystem/SComponent/c_xyz.h"
 
-class WIND_INFLUENCE;
+struct WIND_INFLUENCE;
 
 void dKyw_wether_draw();
 void dKyw_wether_delete();

include/d/d_msg_flow.h

@@ -16,7 +16,7 @@ enum {
 };
 
 class fopAc_ac_c;
-class msg_class;
+struct msg_class;
 
 // all mesg_flow_node structs members might be wrong
 struct mesg_flow_node {