Use of uninitialized value in networkstatus_parse_vote_from_string (src/or/routerparse.c:3533)

Triggered in `22139c0`, compiled with `-fsanitize=memory` and clang 6.0.0-trunk. `./fuzz-consense < test000bbb` ``` ==9293==WARNING: MemorySanitizer: use-of-uninitialized-value #0 0x5611f7f7e4de in networkstatus_parse_vote_from_string /root/tor/src/or/routerparse.c:3533:23 #1 0x5611f75bbbd1 in fuzz_main /root/tor/src/test/fuzz/fuzz_consensus.c:66:8 #2 0x5611f75bb29d in main /root/tor/src/test/fuzz/fuzzing_common.c:179:3 #3 0x7f9914298b44 in __libc_start_main /build/glibc-6V9RKT/glibc-2.19/csu/libc-start.c:287 #4 0x5611f75488ce in _start (/root/tor/src/test/fuzz/fuzz-consensus+0x3bc8ce) SUMMARY: MemorySanitizer: use-of-uninitialized-value /root/tor/src/or/routerparse.c:3533:23 in networkstatus_parse_vote_from_string ```