gcc won't compile 2.3.1 with -Wall -Wextra -pedantic

[Andrew Sayers]

A stray comma means gcc won't compile 2.3.1 if you turn on the above
flags (presumably it's just -pedantic that's complaining, but I'm not
going to do a long series of tests for a typo).  Here's a patch:

diff -ruN mysql++-2.3.1/lib/connection.h mysql++-2.3.1-modified/lib/connection.h
--- mysql++-2.3.1/lib/connection.h	2007-07-11 03:29:47.000000000 +0100
+++ mysql++-2.3.1-modified/lib/connection.h	2007-07-11 16:46:47.000000000 +0100
@@ -479,7 +479,7 @@
 	enum OptionError {
 		opt_err_type,
 		opt_err_value,
-		opt_err_conn,
+		opt_err_conn
 	};
 	
 	/// \brief Drop the connection to the database server