Emit function attribute "coroutine.presplit" for coroutines
Emit function attribute "coroutine.presplit" for coroutines

This fixes issues with recent LLVM revisions that require this
attribute: https://llvm.org/docs/Coroutines.html.

Context:
cl/419786634
https://github.com/llvm/llvm-project/commit/c75cedc237f9747c5d5fe2a312d5ccc8531e2e70
https://reviews.llvm.org/D115790

Bug: b/165000222
Change-Id: I75308c6cf75d7aa9b823e7ded37f3f6ddf0a7010
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/61148
Reviewed-by: Alexis Hétu <1c7141772178a7e80858c3db5052b328076f08f4@google.com>
Kokoro-Result: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Tested-by: Nicolas Capens <51edc787c30f24c4904e8ffbb5523c3a9f7a451d@google.com>

google/swiftshader,google/swiftshader,google/swiftshader