cdr_adaptive_odbc: Fix DNSs mixed config quote quoted_identifiers

cdr_adaptive_odbc: Fix DNSs mixed config quote quoted_identifiers

When haved more than once DNSs config and one of their dont set
quoted_identifiers and before this is with configurated with
quoted_identifiers resulting a truncate statement for a reference null
for quote character identifier.

This patch initializes quoted flag before build SQL Query

Example config for this bugfix case in cdr_adaptive_odbc.conf file

	[first]
	connection=asterisk-server1
	table=cdr
	quoted_identifiers="

	[second]
	connection=asterisk-server2
	table=cdr

	[third]
	connection=asterisk-server3
	table=cdr
	quoted_identifiers=`

Change-Id: Ibd95667b468e10d4a19a2b9d88b9934ec7207e1d