[bobbybasketball1999]

refs libretro/mupen64plus-libretro-nx#431

Currently, the UnbufferedDrawer:

• only enables aTexCoord0 when the combiner uses tile 0
• only enables aTexCoord1 when the combiner uses tile 1

That works out for the "inaccurate" VertexShaderTexturedRectFast shader.

But in the default "accurate" mode, VertexShaderTexturedRect only ever uses aTexCoord0.
So when the combiner uses only tile 1, enabling aTexCoord1 does nothing.
It should enable aTexCoord0 whenever either tile 0 or tile 1 is used.

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Fixes Paper Mario's file load screen.

Reproduced on Windows using:

• Project64-Win32-Dev-4.0.0-6807-777fbdf
• current GLideN64 master
• FORCE_UNBUFFERED_DRAWER enabled

Before:

After: