which: bump to version 2.21

Add hash file and switch to gnu mirror.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/which/which.hash

@@ -0,0 +1,2 @@
+# Locally calculated after checking pgp signature
+sha256	f4a245b94124b377d8b49646bf421f9155d36aa7614b6ebf83705d3ffc76eaad	which-2.21.tar.gz

package/which/which.mk

@@ -4,8 +4,8 @@
 #
 ################################################################################
 
-WHICH_VERSION = 2.20
-WHICH_SITE = http://carlo17.home.xs4all.nl/which
+WHICH_VERSION = 2.21
+WHICH_SITE = $(BR2_GNU_MIRROR)/which
 WHICH_LICENSE = GPLv3+
 WHICH_LICENSE_FILES = COPYING