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

src/d/d_particle.cpp

@@ -1596,7 +1596,7 @@ s32 dPa_control_c::getPolyColor(cBgS_PolyInfo& param_0, int param_1, _GXColor* p
         return 0;
     }
 
-    if (param_1 == NULL) {
+    if (param_1 == 0) {
         dKy_pol_eff_prim_get(&param_0, param_2);
         dKy_pol_eff_env_get(&param_0, param_3);
         *param_4 = dKy_pol_eff_alpha_get(&param_0);