Scrollbars Appear when content fills area that scrollbar would appear in

Nobody has claimed this yet.

When content fills and area (even partially) that a scrollbar would be drawn in, the scrollbars automatically appear, even if the content is not larger than the window/container.

Platform: Linux: x86_64
Rendering Info: GLFW, GLAD, OpenGL 3.3

Example 1 (Default scrollbar is 10px, scrollbar appears):

```
if (nk_begin(ctx, "Demo", nk_rect(0, 0, 800, 600), (nk_flags)NULL))
{
ctx->style.window.padding = {0,0};
ctx->style.window.spacing = {0,0};
ctx->style.button.padding = {0,0};
nk_layout_row_static(ctx, 591, 791, 1);
if (nk_button_label(ctx, "button"))
fprintf(stdout, "button pressed\n");
}
nk_end(ctx);
```

Example 2 (Settings scrollbar to 5px, scrollbar still appears):

```
if (nk_begin(ctx, "Demo", nk_rect(0, 0, 800, 600), (nk_flags)NULL))
{
ctx->style.window.padding = {0,0};
ctx->style.window.spacing = {0,0};
ctx->style.button.padding = {0,0};
ctx->style.window.scrollbar_size = {5,5};
nk_layout_row_static(ctx, 596, 796, 1);
if (nk_button_label(ctx, "button"))
fprintf(stdout, "button pressed\n");
}
nk_end(ctx);
```

Reproduce both examples on Linux with the GLFW, GLAD, and OpenGL 3.3 setup described in the report, comparing the 10px and 5px scrollbar cases. Trace the scrollbar and layout behavior until the fit calculation is located; done means neither example shows a scrollbar when the content fits its window or container.

Written by the indexing model from the issue text.