Use combined installer for targets

appveyor.yml

@@ -1,18 +1,12 @@
 environment:
-  CARGO_TARGET: x86_64-pc-windows-gnu
   matrix:
   - TARGET: x86_64-pc-windows-msvc
   - TARGET: i686-pc-windows-gnu
 install:
-  - ps: Start-FileDownload "https://static.rust-lang.org/dist/rustc-nightly-${env:TARGET}.tar.gz"
-  - ps: Start-FileDownload "https://static.rust-lang.org/cargo-dist/cargo-nightly-${env:CARGO_TARGET}.tar.gz"
-  - 7z x rustc-nightly-%TARGET%.tar.gz > nul
-  - 7z x rustc-nightly-%TARGET%.tar > nul
-  - 7z x cargo-nightly-%CARGO_TARGET%.tar.gz > nul
-  - 7z x cargo-nightly-%CARGO_TARGET%.tar > nul
+  - ps: Start-FileDownload "https://static.rust-lang.org/dist/rust-nightly-${env:TARGET}.exe"
+  - rust-nightly-%TARGET%.exe /VERYSILENT /NORESTART /DIR="C:\Program Files (x86)\Rust"
   - call "C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat" amd64
-  - set PATH=%PATH%;%cd%/rustc-nightly-%TARGET%/rustc/bin
-  - set PATH=%PATH%;%cd%/cargo-nightly-%CARGO_TARGET%/cargo/bin
+  - SET PATH=%PATH%;C:\Program Files (x86)\Rust\bin
   - SET PATH=%PATH%;C:\MinGW\bin
   - rustc -V
   - cargo -V