Include debuginfo in release builds

[bbangert]

We can include debuginfo in our release builds for minimal performance hit, but more meaningful errors.

[bbangert]

rust-lang/rust#49227 has some help on this

[pjenvey]

Copying over my explanation from mozilla-services/syncstorage-rs#91 for reference here:

Took me a while to track this down, we came across it for autopush-rs. There's also a not well documented debug value of either 1 (or 2, but true is the equivalent of 2). This value's passed along to rustc -C debuginfo:

    -C            debuginfo=val -- debug info emission level, 0 = no debug info, 1 = line tables only, 2 = full debug info with variable and type information

debug = 1 sounds ideal for release builds, just producing the line tables

There's been some reports of slowdowns with full release = 2 which may or may not be fixed:

rust-lang/rust#49227

debug = 1 should at the very least reduce the binary size

[pjenvey]

Some additional info here: BurntSushi/ripgrep#413