Fix "GPUTexture: texture alloc failed. Not enough Video Memory." in area resizing

`gpu_texture_try_alloc` invalidates zero-sized textures.
The message in the console is not correct in this case (because it is not due to lack of memory).

source/blender/draw/engines/eevee/eevee_effects.c

@@ -157,7 +157,7 @@ void EEVEE_effects_init(EEVEE_ViewLayerData *sldata, EEVEE_Data *vedata)
 	}
 
 	DRW_framebuffer_init(&fbl->downsample_fb, &draw_engine_eevee_type,
-	                    (int)viewport_size[0] / 2, (int)viewport_size[1] / 2,
+	                    max_ii((int)viewport_size[0] / 2, 1), max_ii((int)viewport_size[1] / 2, 1),
 	                    &texmax, 1);
 
 

source/blender/draw/intern/draw_manager.c

@@ -2308,6 +2308,7 @@ void DRW_framebuffer_init(
         DRWFboTexture textures[MAX_FBO_TEX], int textures_len)
 {
 	BLI_assert(textures_len <= MAX_FBO_TEX);
+	BLI_assert(width > 0 && height > 0);
 
 	bool create_fb = false;
 	int color_attachment = -1;