syslog-ng: fixed build by passing -std=gnu99

Note:

By default the Makefile defines 'CC=gcc -std=gnu99' and because we
automatically pass 'CC=gcc' as make argument which overwrites the
the needed '-std=gnu99' we need to workaround the problem manually

base/syslog-ng/syslog-ng.conf

@@ -20,5 +20,10 @@ else
 	var_append extraconfopt " " "--enable-dynamic-linking"
 fi
 
+# by default the Makefile defines 'CC=gcc -std=gnu99' and because we
+# automatically pass 'CC=gcc' as make argument which overwrites the
+# the needed '-std=gnu99' we need to workaround the problem manually
+CC="gcc -std=gnu99"
+
 hook_add postmake 5 'cp -v $confdir/etc_syslog-ng.conf $root/etc/syslog-ng.conf'