ngage: Remove Nokia N-Gage support.

This can be reverted if a toolchain arrives that can handle C99 features like
variables declared in the middle of a scope, but for now we literally can't
compile SDL3 for this platform.

Fixes #11243.

include/SDL3/SDL_main_impl.h

@@ -131,18 +131,6 @@
 
             /* end of SDL_PLATFORM_WINDOWS impls */
 
-        #elif defined(SDL_PLATFORM_NGAGE)
-            /* same typedef as in ngage SDKs e32def.h */
-            typedef signed int TInt;
-            /* TODO: if it turns out that this only works when built as C++,
-                     move SDL_PLATFORM_NGAGE into the C++ section in SDL_main.h */
-            TInt E32Main()
-            {
-                return SDL_RunApp(0, NULL, SDL_main, NULL);
-            }
-
-            /* end of SDL_PLATFORM_NGAGE impl */
-
         #else /* platforms that use a standard main() and just call SDL_RunApp(), like iOS and 3DS */
             int main(int argc, char *argv[])
             {