xenomai: fix license files variable

In commit 472b07ea8ff1cd341c5f97508e5c29266146fa51 ("xenomai: bump
version to 3.0.3"), the XENOMAI_LICENSE_FILES variable was not
updated, causing a number of build failures. This commit fixes that to
point to existing files.

Fixes:

  http://autobuild.buildroot.net/results/f2cd7cd1f8bcf67c66fb713ef6b03f1f01a74dc5/

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

package/xenomai/xenomai.mk

@@ -15,7 +15,7 @@ XENOMAI_SITE = https://xenomai.org/downloads/xenomai/stable
 XENOMAI_SOURCE = xenomai-$(XENOMAI_VERSION).tar.bz2
 XENOMAI_LICENSE = GPLv2+ with exception (headers), LGPLv2.1+ (libraries), GPLv2+ (kernel), GFDLv1.2+ (docs), GPLv2 (ipipe patch, can driver)
 # GFDL is not included but refers to gnu.org
-XENOMAI_LICENSE_FILES = debian/copyright include/COPYING src/skins/native/COPYING ksrc/nucleus/COPYING
+XENOMAI_LICENSE_FILES = debian/copyright include/COPYING lib/trank/COPYING kernel/cobalt/COPYING
 
 XENOMAI_INSTALL_STAGING = YES
 XENOMAI_INSTALL_TARGET_OPTS = DESTDIR=$(TARGET_DIR) install-user