Cleanup syntax::ext::build

[Mark-Simulacrum]

I suspect most of this code could be inlined but I only removed the bits where the inlining didn't really hurt readability (i.e., method call -> function call) or the completely unused code.

[rust-highfive]

The job mingw-check of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

2019-09-21T19:58:22.1231347Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-09-21T19:58:22.1431483Z ##[command]git config gc.auto 0
2019-09-21T19:58:22.1514614Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-09-21T19:58:22.1572429Z ##[command]git config --get-all http.proxy
2019-09-21T19:58:22.1714853Z ##[command]git -c http.extraheader="AUTHORIZATION: basic ***" fetch --force --tags --prune --progress --no-recurse-submodules --depth=2 origin +refs/heads/*:refs/remotes/origin/* +refs/pull/64670/merge:refs/remotes/pull/64670/merge
---
2019-09-21T20:06:09.8258565Z    Compiling rustc_macros v0.1.0 (/checkout/src/librustc_macros)
2019-09-21T20:06:18.4466068Z     Checking syntax_pos v0.0.0 (/checkout/src/libsyntax_pos)
2019-09-21T20:06:19.8864856Z     Checking rustc_errors v0.0.0 (/checkout/src/librustc_errors)
2019-09-21T20:06:21.1107622Z     Checking fmt_macros v0.0.0 (/checkout/src/libfmt_macros)
2019-09-21T20:06:28.8538686Z error[E0599]: no method named `poly_trait_ref` found for type `&ext::base::ExtCtxt<'a>` in the current scope
2019-09-21T20:06:28.8539056Z    --> src/libsyntax/ext/build.rs:140:39
2019-09-21T20:06:28.8539302Z     |
2019-09-21T20:06:28.8539560Z 140 |         ast::GenericBound::Trait(self.poly_trait_ref(path.span, path),
2019-09-21T20:06:28.8539856Z 
2019-09-21T20:06:29.3176215Z error: aborting due to previous error
2019-09-21T20:06:29.3176325Z 
2019-09-21T20:06:29.3176648Z For more information about this error, try `rustc --explain E0599`.
---
2019-09-21T20:06:29.3800360Z == clock drift check ==
2019-09-21T20:06:29.3811766Z   local time: Sat Sep 21 20:06:29 UTC 2019
2019-09-21T20:06:29.4676673Z   network time: Sat, 21 Sep 2019 20:06:29 GMT
2019-09-21T20:06:29.4676830Z == end clock drift check ==
2019-09-21T20:06:30.6599914Z ##[error]Bash exited with code '1'.
2019-09-21T20:06:30.6632128Z ##[section]Starting: Checkout
2019-09-21T20:06:30.6633603Z ==============================================================================
2019-09-21T20:06:30.6633646Z Task         : Get sources
2019-09-21T20:06:30.6633701Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[petrochenkov]

@bors r+

[bors]

📌 Commit 8417ac6 has been approved by petrochenkov