base32, base64: fix broken tests Problem reported by Bruno Haible in: https://lists.gnu.org/r/bug-gnulib/2021-08/msg00170.html * lib/base32.c, lib/base64.c: Do not include verify.h, and omit all uses of ‘assume’. * modules/base32, modules/base64 (Depends-on): Remove verify. * tests/test-base32.c, tests/test-base64.c: Don’t pass out-of-range values to allocator, as converting them to idx_t relies on implementation-defined behavior that could trap.