Update appveyor script

appveyor.yml

@@ -1,34 +1,44 @@
 environment:
     matrix:
-        - RUST_INSTALL_TRIPLE: i686-pc-windows-gnu
+        - RUST_INSTALL_TOOLCHAIN: gnu
           RUST_CHANNEL: stable
-        - RUST_INSTALL_TRIPLE: x86_64-pc-windows-gnu
-          RUST_CHANNEL: stable
-        - RUST_INSTALL_TRIPLE: x86_64-pc-windows-msvc
+        - RUST_INSTALL_TOOLCHAIN: msvc
           RUST_CHANNEL: nightly
 
 matrix:
     allow_failures:
         - RUST_CHANNEL: nightly
 
+platform:
+    - x86
+    - x64
+
 install:
     - ps: Start-FileDownload "http://static.rust-lang.org/dist/channel-rust-${env:RUST_CHANNEL}"
-    - ps: $env:RUST_INSTALLER = Select-String "${env:RUST_INSTALL_TRIPLE}.*exe" "channel-rust-${env:RUST_CHANNEL}" | select -exp line
+    - ps: |
+          if ($env:PLATFORM -eq "x86") {
+            $env:RUST_INSTALLER = Select-String "i686-pc-windows-${env:RUST_INSTALL_TOOLCHAIN}.*exe" "channel-rust-${env:RUST_CHANNEL}" | select -exp line
+          } else {
+            $env:RUST_INSTALLER = Select-String "x86_64-pc-windows-${env:RUST_INSTALL_TOOLCHAIN}.*exe" "channel-rust-${env:RUST_CHANNEL}" | select -exp line
+          }
     - ps: Start-FileDownload "http://static.rust-lang.org/dist/${env:RUST_INSTALLER}"
     - '%RUST_INSTALLER% /VERYSILENT /NORESTART /DIR="C:\Rust"'
-    - call "C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat" amd64
     - ps: $env:path = "C:\Rust\bin;" + $env:path
     - ps: |
-        if ($env:RUST_INSTALL_TRIPLE -like "x86_64-*-gnu") {
+        if ($env:RUST_INSTALL_TOOLCHAIN -eq "gnu" -And $env:PLATFORM -eq "x64") {
             Start-FileDownload "http://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win64/Personal%20Builds/mingw-builds/5.1.0/threads-win32/seh/x86_64-5.1.0-release-win32-seh-rt_v4-rev0.7z/download" -FileName mingw64.7z
             7z x -oC:\ mingw64.7z > $null
             $env:path = "C:\mingw64\bin;" + $env:path
             gcc --version
         }
-        elseif ($env:RUST_INSTALL_TRIPLE -like "i686-*-gnu") {
+        elseif ($env:RUST_INSTALL_TOOLCHAIN -eq "gnu") {
             $env:path = "C:\mingw\bin;" + $env:path
             gcc --version
         }
+    - ps: |
+        if ($env:PLATFORM -eq "x64") { $env:vcargs = "amd64" }
+        else { $env:vcargs = "x86" }
+    - call "C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\vcvarsall.bat" %vcargs%
     - rustc --version --verbose
     - cargo --version