The configure script should survive not finding lex/flex.

TODO

@@ -149,6 +149,8 @@ server.
 ** Fix configure.in.  The output of ./configure --help isn't as good 
    as it should be.  See libisc.
 
+** The configure script fails if neither flex nor lex can be found.
+
 ** async-text-deleted (and possibly others) should be sent to
    recipients of any of the objects linked to the text that is
    deleted.
@@ -998,4 +1000,3 @@ server.
 Local variables:
 mode: outline
 End:
-