libboost-safe-numerics: Patch downstream/

Clang 18 with libc++ fails with `no member named 'terminate' in namespace
'std'; did you mean 'template'?` due to <exception> not being included.

Reported upstream at boostorg/safe_numerics#139.

downstream/libs/safe_numerics/include/boost/safe_numerics/checked_result_operations.hpp

@@ -20,6 +20,7 @@
 // integer type is an "extended" integer.
 
 #include <cassert>
+#include <exception>
 
 #include <boost/logic/tribool.hpp>