package/botan: fix altivec support

configure.py only supports --disable-altivec.

Fixes
http://autobuild.buildroot.net/results/318/3187afa3eea77e5de0e0fe14717bfc080da08117/

Added license hash URL.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/botan/botan.hash

@@ -1,4 +1,4 @@
-# Locally calculated after checking pgp signature
+# From https://botan.randombit.net/releases/sha256sums.txt
 sha256 e42df91556317588c6ca0e41bf796f9bd5ec5c70e0668e6c97c608c697c24a90  Botan-2.7.0.tgz
 # Locally computed
 sha256 40cfd35a9e34d18463806f57553c968fdbaf254a2e2a636d1d8e32ff6b698495  license.txt

package/botan/botan.mk

@@ -70,9 +70,7 @@ BOTAN_DEPENDENCIES += zlib
 BOTAN_CONF_OPTS += --with-zlib
 endif
 
-ifeq ($(BR2_POWERPC_CPU_HAS_ALTIVEC),y)
-BOTAN_CONF_OPTS += --enable-altivec
-else
+ifeq ($(BR2_POWERPC_CPU_HAS_ALTIVEC),)
 BOTAN_CONF_OPTS += --disable-altivec
 endif