Resolve Coverity issue with Parser::Transition's ownership of Action *.

This commit is somewhat subtle; it informs Coverity that
Parser::Transition only holds an Action* temporarily, and should never
create/delete one.  I believe runtime checkers should also understand
this OK.

Signed-off-by: John Hood <cgull@glup.org>

src/terminal/parser.cc

@@ -63,6 +63,7 @@ std::list<Parser::Action *> Parser::Parser::input( wchar_t ch )
   }
 
   append_or_delete( tx.action, ret );
+  tx.action = NULL;
 
   if ( tx.next_state != NULL ) {
     append_or_delete( tx.next_state->enter(), ret );