Re: type-clash diagnostic wording consistency

[Akim Demaille]

| reader.c generates these two diagnostics:
|   type clash (`T1' `T2') on default action
|   result type clash on merge function F: `T1' vs. `T2'
| 
| It's better if we use consistent wording, so I changed the wording of
| the latter to:
| 
|   result type clash (`T1' `T2') on merge function F

honestly, I prefer the other one: we often have error messages that
are ``constant before the colon, and then a changing part after the
colon´´.  In between quotes, because it's not written down, but merely
the common framework, AFAICS.  Parentheses are not common in my error
message catalogue :)