appveyor: enable x86 build as well.

appveyor.yml

@@ -10,12 +10,14 @@ branches:
   only:
     - master
 
-platform: x64
+platform:
+    - x86
+    - x64
 configuration: Release
 
 build:
 
 build_script:
  - cd c:\projects\assimp
- - cmake CMakeLists.txt -G "Visual Studio 11" 
+ - cmake CMakeLists.txt -G "Visual Studio 11"
  - msbuild /m /p:Configuration=Release /p:Platform="Win32" Assimp.sln