package/botan: security bump to version 2.16

Fix a memory leak in GCM where if passed an unsuitable block cipher (eg
not 128 bit) it would throw an exception and leak the cipher object.

https://github.com/randombit/botan/blob/2.16.0/news.rst

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/botan/botan.hash

@@ -1,4 +1,4 @@
 # From https://botan.randombit.net/releases/sha256sums.txt
-sha256  d88af1307f1fefac79aa4f2f524699478d69ce15a857cf2d0a90ac6bf2a50009  Botan-2.15.0.tar.xz
+sha256  92ed6ebc918d86bd1b04221ca518af4cf29cc326c4760740bd2d22e61cea2628  Botan-2.16.0.tar.xz
 # Locally computed
 sha256  fb7f0322d36fba55ca17d77bc203a9f09a40daa8a249b75cf8887aba36cec9d0  license.txt

package/botan/botan.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-BOTAN_VERSION = 2.15.0
+BOTAN_VERSION = 2.16.0
 BOTAN_SOURCE = Botan-$(BOTAN_VERSION).tar.xz
 BOTAN_SITE = http://botan.randombit.net/releases
 BOTAN_LICENSE = BSD-2-Clause