bitflags crate is using deprecated try macro

[johalun]

Compile warning on Linux. Look into if we need a newer version of bitflags.

warning: use of deprecated macro `try`: use the `?` operator instead
  --> src/ctl_flags.rs:6:1
   |
6  | / bitflags! {
7  | |     pub struct CtlFlags : libc::c_uint {
8  | |         /// Allow reads of variable
9  | |         const RD = CTLFLAG_RD;
...  |
69 | |     }
70 | | }
   | |_^
   |
   = note: `#[warn(deprecated)]` on by default
   = note: this warning originates in the macro `__impl_bitflags` (in Nightly builds, run with -Z macro-backtrace for more info)

[asomers]

I can't reproduce this. Maybe bitflags fixed it upstream?