log schema parsing errors into a single buffer

[aakash10292]

This simple patch gets rid of a redundant buffer (syntax_err) to which we log errors encountered while parsing schema. Turns out we also always log those errors to the err buffer as well. So we can reliably fetch the same errors from csc2_get_err. A useful side-effect is a more informative rc 240 error encountered while trying to index on blob/UTF-8 fields