Backtrace line numbers

[lynaghk]

First, let me say thanks for Neon --- it's a great project and it allowed me to really dive in and make my first Rust project, Finda.

I'm trying to compile my project so that I have a release build that logs line numbers and backtraces on panic.
I can do this fine with a standard Rust binary, but I can't figure it out with Neon.

Here's a minimal reproducible example repository.
I've included the build details below.

Thanks!

---

On OS X 10.9.5, Rust can compile a release binary that includes line numbers in the backtrace:

cd native/a_panic
cargo run --release

Output:

2018-05-08 15:22:34 ERROR [log_panics] thread 'main' panicked at 'oh no!': src/lib.rs:7
stack backtrace:
   0:        0x1000fba9e - backtrace::backtrace::trace::h6954c675fdb81650
                        at /Users/dev/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.7/src/backtrace/libunwind.rs:53
   1:        0x1000fa01c - backtrace::capture::Backtrace::new::h44f202edd8c21d9b
                        at /Users/dev/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.7/src/capture.rs:88
...

However, the same code compiled with Neon has no line numbers in the backtrace:

yarn install
node -e 'require("./")'

Output:

2018-05-08 15:27:42 ERROR [log_panics] thread 'unnamed' panicked at 'oh no!': a_panic/src/lib.rs:7
stack backtrace:
   0:        0x106de4e6e - backtrace::backtrace::trace::ha74a84b436b4090e
   1:        0x106de299c - backtrace::capture::Backtrace::new::h180d14cb08d60248
   2:        0x106de1eed - log_panics::init::_$u7b$$u7b$closure$u7d$$u7d$::h990ff31ff59f1e7d
   3:        0x106e12870 - std::panicking::rust_panic_with_hook::hfb431ab23831437f
   4:        0x106dd8821 - std::panicking::begin_panic::h6ef215fe9e0c41fe
   5:        0x106dd878d - a_panic::panic_please::h8d3d02c8208552ed
   6:        0x106dc9cb5 - backtrace_test::hello::hb394c4370bb7ceec
   7:        0x106dc9e5b - std::panicking::try::do_call::h5c5f1cbb0951adfa (.llvm.5600580859378085660)
   8:        0x106e2d38e - __rust_maybe_catch_panic
...

The output is the same, even when using the --debug flag:

yarn run -- neon build --debug
node -e 'require("./")'

or when adding

[profile.release]
debug = true

to Cargo.toml.