I implemented this extension as part of swiftshader-cl/51589 but had not
exposed it as a supported extension. This worked fine when loading
SwiftShader directly, but I need to now load it via the loader.

Bug: b/176981107
Change-Id: I494be7154b04186e51ee380e16b60b88ff9c9d30
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/52751Tested-by: Antonio Maiorano <amaiorano@google.com>
Kokoro-Result: Antonio Maiorano <amaiorano@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>