message: Fix a bug with float16->uint8 convert
diff: @@ -6218,6 +6218,7 @@ static llvm::Value *lTypeConvAtomic(FunctionEmitContext *ctx, llvm::Value *exprV
  PerformanceWarning(pos, "Conversion from float16 to unsigned int is slow. Use \"int\" if possible");
  cast = ctx->CastInst(llvm::Instruction::FPToUI, // unsigned int
  exprVal, targetType, cOpName);
  + break;
  case AtomicType::TYPE_FLOAT:
  if (fromType->IsVaryingType())
  PerformanceWarning(pos, "Conversion from float to unsigned int is slow. Use \"int\" if possible");
  