Update expected test output. Spurious changes in some error messages.

test/bad/duplicate-formal.expected

 File "duplicate-formal.mly", line 6, characters 0-3:
-Error: several parameters of this rule are named "X27".
+Error: several parameters of this rule are named "X31".

test/bad/unification-error-in-args.expected

 File "unification-error-in-args.mly", line 7, characters 6-7:
-Error: does the symbol "X27" expect 0 or 1 argument?
+Error: does the symbol "X31" expect 0 or 1 argument?