[libteken] Add missing initialization in the fuzz target (#821).

Fixes https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=2602
and also resolves https://github.com/google/oss-fuzz/issues/821

projects/libteken/libteken_fuzzer.c

@@ -24,7 +24,7 @@ static teken_funcs_t tf = {
 };
 
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
-  teken_t t;
+  teken_t t = { 0 };
   teken_init(&t, &tf, NULL);
   teken_input(&t, data, size);
   return 0;