Update appveyor.yml

appveyor.yml

@@ -28,9 +28,16 @@ install:
 - call c:\projects\assimp\scripts\appveyor\compiler_setup.bat
 
 build_script:
- - cd c:\projects\assimp
- - cmake CMakeLists.txt -G "Visual Studio %Configuration%"
- - if "%platform%" EQU "x64" (msbuild /m /p:Configuration=Release /p:Platform="x64" Assimp.sln) else (msbuild /m /p:Configuration=Release /p:Platform="Win32" Assimp.sln)
+build_script:  
+- cmd: >-
+    cd c:\projects\assimp
+    if "%platform%" equ "x64" (
+      cmake CMakeLists.txt -G "Visual Studio %Configuration% Win64"
+      msbuild /m /p:Configuration=Release /p:Platform="x64" Assimp.sln
+    ) else (
+      cmake CMakeLists.txt -G "Visual Studio %Configuration%"
+      msbuild /m /p:Configuration=Release /p:Platform="Win32" Assimp.sln
+    ) 
 
 after_build:
   - 7z a assimp.7z c:\projects\assimp\bin\release\* c:\projects\assimp\lib\release\*