botan: fixed by adding '--cpu=$arch_machine' while configuring so it can properly use the optimized code for the target architecture (see note)

Note:

Without using the '--cpu' configure option the configure script will try to
guess for what architecture the code should be optimized.
The problem was noticed while trying to build an i686 target on x86-64 build
host, which utterly failed without properly specifying the target architecture.

security/botan/botan.conf

@@ -13,5 +13,5 @@
 # GNU General Public License can be found in the file COPYING.
 # --- SDE-COPYRIGHT-NOTE-END ---
 
-hook_add preconf 5 "./configure.py --prefix=/$prefix --libdir=${libdir##*/}"
+hook_add preconf 5 "./configure.py --prefix=/$prefix --libdir=${libdir##*/} --cpu=$arch_machine"
 var_append makeinstopt ' ' "DOCDIR=$docdir"