[clang-format] Handle unions like structs and classes

[HazardyKnusperkeks]

Summary

There is no reason why unions should be handled differently, I think they are just forgotten since they are not used that often.

No test case added, since that would be complicated to produce.

[owenpan]

LGTM

clang/lib/Format/TokenAnnotator.cpp

unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
   if (Right.is(TT_PointerOrReference))
     return 190;
   if (Right.is(TT_LambdaArrow))
     return 110;
   if (Left.is(tok::equal) && Right.is(tok::l_brace))
     return 160;
   if (Left.is(TT_CastRParen))
     return 100;
-  if (Left.isOneOf(tok::kw_class, tok::kw_struct))
+  if (Left.isOneOf(tok::kw_class, tok::kw_struct, tok::kw_union))
     return 5000;
   if (Left.is(tok::comment))
     return 1000;
 
   if (Left.isOneOf(TT_RangeBasedForLoopColon, TT_InheritanceColon,
                    TT_CtorInitializerColon)) {
     return 2;
   }