Problem with SQL_C_WCHAR in ODBC module

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=5595

Reported by Marcus Wellhardh wellhard@roxen.com

Queries that returns SQL_C_WCHAR does not work in Pike 7.4, example with ODBC_DEBUG enabled:

> db->query("select count(*) as antal from maincategory2");
ODBC:execute: SQLExecDirect returned 0, cols 1, rows -1
ODBC:odbc_fix_fields():
name:antal
name_len:5
sql_type:4
precision:10
scale:0
nullable:1
SQL_C_WCHAR
ODBC:fetch_row(): Field 1: WCHAR not supported.
ODBC:fetch_row(): NO DATA FOUND
(3) Result: ({ /* 1 element */
                ([ /* 2 elements */
                  ".antal":"",
                  "antal":""
                ])
            })

The same query works in Pike 7.8, it should therefore be fixable with some backporting.

Reported in [RT 15875].