Corrupted backtrace example

1. Configure memory.x and default target for your board
2. cargo run
3. Continue until Breakpoint 3, rust_begin_unwind
4. Run bt in GDB:

  (gdb) bt
  #0  rust_begin_unwind (_info=0x2000ff18)
      at /home/mabez/.cargo/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/panic-halt-0.2.0/src/lib.rs:32
  #1  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #2  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #3  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #4  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #5  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #6  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #7  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #8  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #9  0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #10 0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #11 0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #12 0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #13 0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #14 0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  #15 0x08000640 in core::panicking::panic_fmt () at src/libcore/panicking.rs:84
  --Type <RET> for more, q to quit, c to continue without paging--