[clang] [llvm] [clang][HLSL][SPRI-V] Add convergence intrinsics (PR #80680)

[Nathan Gauër via cfe-commits]

================
@@ -1295,11 +1295,13 @@ double4 trunc(double4);
 /// true, across all active lanes in the current wave.
 _HLSL_AVAILABILITY(shadermodel, 6.0)
 _HLSL_BUILTIN_ALIAS(__builtin_hlsl_wave_active_count_bits)
+__attribute__((convergent))
----------------
Keenuts wrote:

@llvm-beanz FYI. Seems like I'll remove it then.

https://github.com/llvm/llvm-project/pull/80680