gettext: fix legal info

The license is wrong, it's GPLv3+ rather than GPLv2+ now.
Also there's a specific clause for libintl that makes it LGPLv2.1+, see
gettext-runtime/COPYING.

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

package/gettext/gettext.mk

@@ -8,8 +8,8 @@ GETTEXT_VERSION = 0.19.6
 GETTEXT_SITE = $(BR2_GNU_MIRROR)/gettext
 GETTEXT_SOURCE = gettext-$(GETTEXT_VERSION).tar.xz
 GETTEXT_INSTALL_STAGING = YES
-GETTEXT_LICENSE = GPLv2+
-GETTEXT_LICENSE_FILES = COPYING
+GETTEXT_LICENSE = LGPLv2.1+ (libintl), GPLv3+ (the rest)
+GETTEXT_LICENSE_FILES = COPYING gettext-runtime/intl/COPYING.LIB
 
 GETTEXT_DEPENDENCIES = $(if $(BR2_PACKAGE_LIBICONV),libiconv)
 HOST_GETTEXT_DEPENDENCIES = # we don't want the libiconv dependency