Performance tests seem to be broken

[Robbepop]

As already stated in bytecodealliance/wasmparser#216 under Benchmarks I am not able to run benchmarks for wasmparser on the current master.

At least I get the following output on cargo bench with RUST_BACKTRACE=1:

Benchmarking it works benchmark: Warming up for 3.0000 sthread 'main' panicked at 'unexpected error Bad magic number (at offset 0)', benches/benchmark.rs:38:42
stack backtrace:
   0: backtrace::backtrace::libunwind::trace
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1: backtrace::backtrace::trace_unsynchronized
             at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2: std::sys_common::backtrace::_print_fmt
             at src/libstd/sys_common/backtrace.rs:78
   3: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
             at src/libstd/sys_common/backtrace.rs:59
   4: core::fmt::write
             at src/libcore/fmt/mod.rs:1069
   5: std::io::Write::write_fmt
             at src/libstd/io/mod.rs:1537
   6: std::sys_common::backtrace::_print
             at src/libstd/sys_common/backtrace.rs:62
   7: std::sys_common::backtrace::print
             at src/libstd/sys_common/backtrace.rs:49
   8: std::panicking::default_hook::{{closure}}
             at src/libstd/panicking.rs:198
   9: std::panicking::default_hook
             at src/libstd/panicking.rs:218
  10: std::panicking::rust_panic_with_hook
             at src/libstd/panicking.rs:477
  11: rust_begin_unwind
             at src/libstd/panicking.rs:385
  12: std::panicking::begin_panic_fmt
             at src/libstd/panicking.rs:339
  13: criterion::Bencher<M>::iter
  14: <criterion::routine::Function<M,F,T> as criterion::routine::Routine<M,T>>::warm_up
  15: criterion::routine::Routine::sample
  16: criterion::analysis::common
  17: criterion::benchmark_group::BenchmarkGroup<M>::bench_function
  18: criterion::Criterion<M>::bench_function
  19: benchmark::main
  20: std::rt::lang_start::{{closure}}
  21: std::rt::lang_start_internal::{{closure}}
             at src/libstd/rt.rs:52
  22: std::panicking::try::do_call
             at src/libstd/panicking.rs:297
  23: std::panicking::try
             at src/libstd/panicking.rs:274
  24: std::panic::catch_unwind
             at src/libstd/panic.rs:394
  25: std::rt::lang_start_internal
             at src/libstd/rt.rs:51
  26: main
  27: __libc_start_main
  28: _start
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: bench failed

[alexcrichton]

I think this has since been fixed, so closing.