mesa/st: handle the internal format GL_BGRA8_EXT just like GL_BGRA

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
15 jobs for !550 with add_apple_texture_format_BGRA8888 in 10 minutes and 37 seconds (queued for 2 seconds)
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Status Job ID Name Coverage
  Containers Build
passed #202353
ubuntu

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  Build+Test
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autotools

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meson-clang

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meson-gallium-clover-llvm

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meson-gallium-clover-llvm39

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meson-gallium-drivers-other

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meson-gallium-radeonsi

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meson-gallium-st-other

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meson-gallium-swr

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meson-glvnd

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meson-loader-classic-dri

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meson-vulkan

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scons-llvm

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scons-nollvm

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scons-swr

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