Fix enum namespace change

[bvssvni]

See PistonDevelopers/piston#719

[bvssvni]

Getting these errors:

<quote expansion>:10:271: 10:344 error: unresolved name `__gfx_extern_crate_hack::gfx::attrib::FloatSubType::Default`.
<quote expansion>:10                                                                                                                                                                                  name_504,ctxt_0::name_71,ctxt_0::name_510,ctxt_0::name_511,ctxt_0::name_512,ctxt_0(name_504,ctxt_0::name_71,ctxt_0::name_510,ctxt_0::name_508,ctxt_0,
                                                                                                                                                                                                                                                                                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: in expansion of #[vertex_format]
src/g2d.rs:113:1: 113:17 note: expansion site
<quote expansion>:10:271: 10:344 error: unresolved name `__gfx_extern_crate_hack::gfx::attrib::FloatSubType::Default`.
<quote expansion>:10                                                                                                                                                                                  name_542,ctxt_0::name_71,ctxt_0::name_510,ctxt_0::name_511,ctxt_0::name_512,ctxt_0(name_542,ctxt_0::name_71,ctxt_0::name_510,ctxt_0::name_508,ctxt_0,
                                                                                                                                                                                                                                                                                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: in expansion of #[vertex_format]
src/g2d.rs:116:1: 116:17 note: expansion site
<quote expansion>:10:271: 10:344 error: unresolved name `__gfx_extern_crate_hack::gfx::attrib::FloatSubType::Default`.
<quote expansion>:10                                                                                                                                                                                  name_551,ctxt_0::name_71,ctxt_0::name_510,ctxt_0::name_511,ctxt_0::name_512,ctxt_0(name_551,ctxt_0::name_71,ctxt_0::name_510,ctxt_0::name_508,ctxt_0,
                                                                                                                                                                                                                                                                                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
note: in expansion of #[vertex_format]
src/g2d.rs:119:1: 119:17 note: expansion site
error: aborting due to 3 previous errors
Could not compile `gfx_graphics`.

[bvssvni]

Perhaps __gfx_extern_crate_hack causes some problems?

[bvssvni]

https://github.com/gfx-rs/gfx-rs/blob/8a935c84b67f4efed90eb8e4e82c354eed091a37/src/gfx_macros/vertex_format.rs#L95

[bvssvni]

Perhaps the enum namespace change does not work properly with extern crate "gfx" as _gfx such as here https://github.com/gfx-rs/gfx-rs/blob/8a935c84b67f4efed90eb8e4e82c354eed091a37/src/gfx_macros/lib.rs#L177

[bvssvni]

It might be I'm on and "old" rustc. Got lots of other errors now.

[bvssvni]

This should be fixed now.