db2_ldap: fix compiler warnings #612

> CC (gcc) [M db2_ldap.so]		ld_fld.o
> In file included from /usr/include/string.h:25:0,
>                  from ../../str.h:24,
>                  from ld_cfg.h:30,
>                  from ld_fld.h:37,
>                  from ld_fld.c:39:
> /usr/include/features.h:148:3: warning: #warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE" [-Wcpp]
>  # warning "_BSD_SOURCE and _SVID_SOURCE are deprecated, use _DEFAULT_SOURCE"

(cherry picked from commit 08927c9)

modules/db2_ldap/ld_fld.c

@@ -35,6 +35,7 @@
 #define _SVID_SOURCE 1 /* timegm */
 
 #define _BSD_SOURCE /* snprintf */
+#define _DEFAULT_SOURCE 1 /* _BSD_SOURCE is deprecated */
 
 #include "ld_fld.h"