mail/thinderbird build failure NetBSD-9.1-stable amd64

[Mike Pumford <mpumford%mudcovered.org.uk@localhost>]

Fails compiling some rust code:

-C codegen-units=1`
error: expected literal
  --> servo/components/style_traits/viewport.rs:12:1
   |
12 | / define_css_keyword_enum! {
13 | |     pub enum UserZoom {
14 | |         Zoom = "zoom",
15 | |         Fixed = "fixed",
16 | |     }
17 | | }
   | |_^
   |
   = note: this error originates in a macro (in Nightly builds, run 
with -Z macro-backtrace for more info)

error: expected literal
  --> servo/components/style_traits/viewport.rs:19:1
   |
19 | / define_css_keyword_enum! {
20 | |     pub enum Orientation {
21 | |         Auto = "auto",
22 | |         Portrait = "portrait",
23 | |         Landscape = "landscape",
24 | |     }
25 | | }
   | |_^
   |
   = note: this error originates in a macro (in Nightly builds, run 
with -Z macro-backtrace for more info)

error[E0425]: cannot find value `MAX_LENGTH` in module `cssparser_internal`
  --> servo/components/style_traits/viewport.rs:12:1
   |
12 | / define_css_keyword_enum! {
13 | |     pub enum UserZoom {
14 | |         Zoom = "zoom",
15 | |         Fixed = "fixed",
16 | |     }
17 | | }
   | |_^ not found in `cssparser_internal`
   |
   = note: this error originates in a macro (in Nightly builds, run 
with -Z macro-backtrace for more info)

error[E0425]: cannot find value `MAX_LENGTH` in module `cssparser_internal`
  --> servo/components/style_traits/viewport.rs:19:1
   |
19 | / define_css_keyword_enum! {
20 | |     pub enum Orientation {
21 | |         Auto = "auto",
22 | |         Portrait = "portrait",
23 | |         Landscape = "landscape",
24 | |     }
25 | | }
   | |_^ not found in `cssparser_internal`
   |
   = note: this error originates in a macro (in Nightly builds, run 
with -Z macro-backtrace for more info)

error: aborting due to 4 previous errors

Fallout from the latest rust compiler update?

Mike