Add standard file header comment to quotes.c.

src/port/quotes.c

+/*-------------------------------------------------------------------------
+ *
+ * quotes.c
+ *	  string quoting and escaping functions
+ *
+ * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/port/quotes.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
 #include "c.h"
 
 /*