Changed the 'module' field length to 20 in the log_display table (Bug #5419).

Previous commit message in 1.6 stable should read 'log_display table' instead
of 'log' table. Both fixes are identical and carried over to HEAD via a merge.

lib/db/postgres7.sql

@@ -272,7 +272,7 @@ CREATE INDEX prefix_log_info_idx ON prefix_log (info);
 
 CREATE TABLE prefix_log_display (
    id SERIAL PRIMARY KEY,
-   module varchar(30) NOT NULL default '',
+   module varchar(20) NOT NULL default '',
    action varchar(40) NOT NULL default '',
    mtable varchar(30) NOT NULL default '',
    field varchar(50) NOT NULL default ''