Support event names shadowing type identifiers

SystemVerilog allows a declaration in an inner scope to use the same name as a
type identifier from an outer scope. This also applies to named event
declarations. The lexer reports such names as `TYPE_IDENTIFIER` before the
event has been installed, which made constructs such as:

    typedef int T;
    module test;
      event T;
    endmodule

fail in the event declaration grammar.

Event declarations do not have the local type/name ambiguity that exists for
variable, net, or parameter declarations. The name in `event_variable` is
always the event name. Use `identifier_name` so a `TYPE_IDENTIFIER` token can
be accepted as the event name.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>

parse.y

@@ -6368,7 +6368,7 @@ dimensions
   ;
 
 event_variable
-  : IDENTIFIER dimensions_opt
+  : identifier_name dimensions_opt
       { if ($2) {
 	      yyerror(@2, "sorry: event arrays are not supported.");
 	      delete $2;