This extension is believed to no longer be required. Note
GL_EXT_texture_format_BGRA8888 offers similar (but not identical)
functionality.

Bug: b/147536183
Change-Id: Id58c62f5ab2fddb3f99e43a9ab74a5929d29983a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/40108
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>