Test on MinGW and MSVC

appveyor.yml

@@ -1,7 +1,19 @@
+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/rust-nightly-i686-pc-windows-gnu.exe'
-  - rust-nightly-i686-pc-windows-gnu.exe /VERYSILENT /NORESTART /DIR="C:\Program Files (x86)\Rust"
-  - SET PATH=%PATH%;C:\Program Files (x86)\Rust\bin
+  - 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
+  - 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:\MinGW\bin
   - rustc -V
   - cargo -V