Examples: made examples's main.cpp consistent with returning 1 on error.

examples/example_sdl2_vulkan/main.cpp

@@ -349,7 +349,7 @@ int main(int, char**)
     if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0)
     {
         printf("Error: %s\n", SDL_GetError());
-        return -1;
+        return 1;
     }
 
     // From 2.0.18: Enable native IME.
@@ -364,7 +364,7 @@ int main(int, char**)
     if (window == nullptr)
     {
         printf("Error: SDL_CreateWindow(): %s\n", SDL_GetError());
-        return -1;
+        return 1;
     }
 
     ImVector<const char*> extensions;