empty: add license information

Signed-off-by: Simon Dawson <spdawson@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/empty/empty.mk

@@ -6,6 +6,8 @@
 EMPTY_VERSION = 0.6.18b
 EMPTY_SOURCE = empty-$(EMPTY_VERSION).tgz
 EMPTY_SITE = http://downloads.sourceforge.net/project/empty/empty/empty-$(EMPTY_VERSION)
+EMPTY_LICENSE = BSD-3c
+EMPTY_LICENSE_FILES = COPYRIGHT
 
 define EMPTY_BUILD_CMDS
 	$(MAKE) $(TARGET_CONFIGURE_OPTS) -C $(@D) all