Use of unitialized value in token_check_object (src/or/parsecommon.c:224)

Triggered in `22139c0`, compiled with `-fsanitize=memory` and clang 6.0.0-trunk. `./fuzz-consensus < test00d68` ``` =9591==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x55ca86e51348 in token_check_object /root/tor/src/or/parsecommon.c:224:13 #1 0x55ca86e51348 in get_next_token /root/tor/src/or/parsecommon.c:397 #2 0x55ca86e3ff83 in tokenize_string /root/tor/src/or/parsecommon.c:72:11 #3 0x55ca8711139a in networkstatus_parse_vote_from_string /root/tor/src/or/routerparse.c:3417:7 #4 0x55ca8676fbd1 in fuzz_main /root/tor/src/test/fuzz/fuzz_consensus.c:66:8 #5 0x55ca8676f29d in main /root/tor/src/test/fuzz/fuzzing_common.c:179:3 #6 0x7f32a84f2b44 in __libc_start_main /build/glibc-6V9RKT/glibc-2.19/csu/libc-start.c:287 #7 0x55ca866fc8ce in _start (/root/tor/src/test/fuzz/fuzz-consensus+0x3bc8ce) SUMMARY: MemorySanitizer: use-of-uninitialized-value /root/tor/src/or/parsecommon.c:224:13 in token_check_object ```