package/ncftp: use correct SPDX license code

According to https://spdx.org/licenses/, the correct license code for
the "Clarified Artistic License" is ClArtistic.

The only other package in Buildroot containing code under this license
is google-breakpad, and it is already using the ClArtistic SPDX code.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
(cherry picked from commit 2ca698051c50546a70e9f7b625f2ee9a2a6a2840)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/ncftp/ncftp.mk

@@ -8,7 +8,7 @@ NCFTP_VERSION = 3.2.7
 NCFTP_SOURCE = ncftp-$(NCFTP_VERSION)-src.tar.xz
 NCFTP_SITE = https://www.ncftp.com/public_ftp/ncftp
 NCFTP_TARGET_BINS = ncftp
-NCFTP_LICENSE = Clarified Artistic License
+NCFTP_LICENSE = ClArtistic
 NCFTP_LICENSE_FILES = doc/LICENSE.txt
 
 NCFTP_DEPENDENCIES = host-autoconf