Tightened validation a bit in oils_cstore.c:

Tightened validation a bit in oils_cstore.c:

1. Issue a warning if the SELECT list is empty for a given table alias
(other than the core class).  This happens when we try to do the
equivalent of SELECT * for a non-core class.

2. Return an error if the generated SELECT list is empty.  This can happen
in a case like the following:

	{
    	"select":{ "aout":null },
        "from":{ "aou":"aout" }
	}

...because there is nothing from the core class, and we don't build default
SELECT lists for non-core classes.

git-svn-id: svn://svn.open-ils.org/ILS/trunk@13785 dcc99617-32d9-48b4-a31d-7c20da2025e4