[clang] [diagtool] Make the BuiltinDiagnosticsByID table sorted (PR #120321)

[Björn Pettersson via cfe-commits]

bjope wrote:

Added some reviewers based on people that have touched code related to "diagnostics" (but don't really know much about the fix, nor who might know anything about this particular code in diagtool). Feel free to redirect to someone else (or let me know if I should try to find other reviewers).

https://github.com/llvm/llvm-project/pull/120321