[clang] [clang] convergent attribute does not require "all threads" (PR #135803)

[Sameer Sahasrabuddhe via cfe-commits]

ssahasra wrote:

Taking the liberty to commit this change without waiting for a review. The change is self-contained, and actually does eliminate a legacy description that is best left to each language spec. 

https://github.com/llvm/llvm-project/pull/135803