Bug#41728: Dropped symbol but no soname change

Restore a stub of the removed mysql_odbc_escape_string function
to fix a ABI breakage. The function was intended to be private
and used only by Connector/ODBC, but, unfortunately, it was exported
as part of the ABI. Nonetheless, only a stub is restored as the
original function is inherently broken and shouldn't be used.

This restoration only applies to MySQL 5.0. This will be addressed
differently in later versions -- reworked library versioning.

include/mysql.h

@@ -550,6 +550,16 @@ unsigned long STDCALL mysql_real_escape_string(MYSQL *mysql,
 					       char *to,const char *from,
 					       unsigned long length);
 void		STDCALL mysql_debug(const char *debug);
+char *		STDCALL mysql_odbc_escape_string(MYSQL *mysql,
+						 char *to,
+						 unsigned long to_length,
+						 const char *from,
+						 unsigned long from_length,
+						 void *param,
+						 char *
+						 (*extend_buffer)
+						 (void *, char *to,
+						  unsigned long *length));
 void 		STDCALL myodbc_remove_escape(MYSQL *mysql,char *name);
 unsigned int	STDCALL mysql_thread_safe(void);
 my_bool		STDCALL mysql_embedded(void);

libmysql/libmysql.c

@@ -1613,6 +1613,18 @@ mysql_real_escape_string(MYSQL *mysql, char *to,const char *from,
   return escape_string_for_mysql(mysql->charset, to, 0, from, length);
 }
 
+
+char * STDCALL
+mysql_odbc_escape_string(MYSQL *mysql,
+			 char *to, ulong to_length,
+			 const char *from, ulong from_length,
+			 void *param,
+			 char * (*extend_buffer)
+			 (void *, char *, ulong *))
+{
+  return NULL;
+}
+
 void STDCALL
 myodbc_remove_escape(MYSQL *mysql,char *name)
 {

libmysql/libmysql.def

@@ -78,6 +78,7 @@ EXPORTS
 	mysql_next_result
 	mysql_num_fields
 	mysql_num_rows
+	mysql_odbc_escape_string
 	mysql_options
 	mysql_stmt_param_count
 	mysql_stmt_param_metadata

libmysqld/libmysqld.def

@@ -71,6 +71,7 @@ EXPORTS
 	mysql_next_result
 	mysql_num_fields
 	mysql_num_rows
+	mysql_odbc_escape_string
 	mysql_options
 	mysql_ping
 	mysql_query