lz4: fix legal info

It moved, and programs are GPLv2+. Fixes:
http://autobuild.buildroot.net/results/70a/70a526b265bb16a6be9f25c5044c65070706171c/

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/lz4/lz4.mk

@@ -7,8 +7,8 @@
 LZ4_VERSION = r131
 LZ4_SITE = $(call github,Cyan4973,lz4,$(LZ4_VERSION))
 LZ4_INSTALL_STAGING = YES
-LZ4_LICENSE = BSD-2c
-LZ4_LICENSE_FILES = LICENSE
+LZ4_LICENSE = BSD-2c (library), GPLv2+ (programs)
+LZ4_LICENSE_FILES = lib/LICENSE programs/COPYING
 
 ifeq ($(BR2_STATIC_LIBS),y)
 define LZ4_DISABLE_SHARED