Fixed building Vivante video driver

src/video/vivante/SDL_vivantevulkan.h

@@ -35,7 +35,7 @@
 
 int VIVANTE_Vulkan_LoadLibrary(SDL_VideoDevice *_this, const char *path);
 void VIVANTE_Vulkan_UnloadLibrary(SDL_VideoDevice *_this);
-SDL_bool VIVANTE_Vulkan_GetInstanceExtensions(SDL_VideoDevice *_this,
+char const* const* VIVANTE_Vulkan_GetInstanceExtensions(SDL_VideoDevice *_this,
                                               unsigned *count,
                                               const char **names);
 SDL_bool VIVANTE_Vulkan_CreateSurface(SDL_VideoDevice *_this,