More GCC compatibility/warning fixes (#3118)

* Wrap >4-char literals in a MULTI_CHAR macro

Modern compilers do not support CW's non-standard behavior with
>4 char literals. We can, however, use a constexpr function to
compute the u64 values directly. This leaves <=4 char literals
unchanged.

* Replace non-pointer usages of NULL with 0

* Define NULL to nullptr on C++11 and above

* Fix more -Wpointer-arith and -Woverflow warnings

* Replace u32/s32 with uintptr_t/intptr_t where appropriate

* JSUOutputStream: Overload all standard int types

include/f_op/f_op_actor.h

@@ -199,7 +199,7 @@ public:
     BOOL chkCondition(u16 condition) { return (mCondition & condition) == condition; }
 
     void suspendProc(void* actor) {
-        if (field_0x10 != NULL) {
+        if (field_0x10 != 0) {
             field_0x14(actor);
         }
     }

include/f_op/f_op_actor_mng.h

@@ -423,7 +423,14 @@ inline BOOL fopAcM_CULLSIZE_IS_BOX(int i_culltype) {
            i_culltype == fopAc_CULLBOX_CUSTOM_e;
 }
 
-inline const cXyz& fopAcM_getCullSizeSphereCenter(const fopAc_ac_c* i_actor) {
+inline
+#ifdef __MWERKS__
+// In the original code, this constructs a temporary and returns a reference to it
+const cXyz&
+#else
+const Vec&
+#endif
+fopAcM_getCullSizeSphereCenter(const fopAc_ac_c* i_actor) {
     return i_actor->cull.sphere.center;
 }
 

include/f_op/f_op_scene_mng.h

@@ -4,14 +4,15 @@
 #include "f_op/f_op_scene_pause.h"
 #include "f_pc/f_pc_manager.h"
 #include "f_op/f_op_scene.h"
+#include <cstdint>
 
 typedef struct base_process_class base_process_class;
 
 scene_class* fopScnM_SearchByID(fpc_ProcID id);
 int fopScnM_ChangeReq(scene_class* i_scene, s16 i_procName, s16 param_3, u16 param_4);
 fpc_ProcID fopScnM_DeleteReq(scene_class* i_scene);
-int fopScnM_CreateReq(s16 i_procName, s16 param_2, u16 param_3, u32 i_data);
-u32 fopScnM_ReRequest(s16 i_procName, u32 i_data);
+int fopScnM_CreateReq(s16 i_procName, s16 param_2, u16 param_3, uintptr_t i_data);
+u32 fopScnM_ReRequest(s16 i_procName, uintptr_t i_data);
 void fopScnM_Management();
 void fopScnM_Init();