WL#1017: Add "AS" data to

Affects: Server-4.1   —   Status: Complete

UDF_ARGS needs to be extended so that the arguement attributes are provided to a
For example:
SELECT udf_func(foo, dog as hushpuppy, manchu) FROM bar;
Would push in the attribute names of "foo", "hushpuppy" and "manchu" into the
The UDF_ARGS structure would now be:
typedef struct st_udf_args
        unsigned int arg_count;               /* Number of arguments */
        enum Item_result *arg_type;           /* Pointer to item_results */
        char **args;                          /* Pointer to argument */
        unsigned long *lengths;               /* Length of string arguments */
        char *maybe_null;                     /* Set to 1 for all maybe_null args */
        char **attributes;                    /* Pointer to attribute name */
        unsigned long *attribute_lengths;     /* Length of attribute arguments */
INSERT INTO blah (foo) VALUES (udf_func("stuff"));
UDF_ARGS would have the string value for the insertion attribute.

The attribute names should not be mutable by the UDF.