Merge pull request #808 from Gol-D-Ace/CI_speedup_build

CI: Speedup msbuild by using all CPU cores

appveyor.yml

@@ -24,8 +24,8 @@ install:
   - cmake -G "Visual Studio 14 2015 Win64" -DCOPIED_DEPENDENCIES=false -DCOPY_DEPENDENCIES=true -DBUILD_CAPTIONS=true -DCOMPILE_D3D12_HOOK=true ..
 
 build_script:
-  - call msbuild /p:Configuration=%build_config% C:\projects\obs-studio\build32\obs-studio.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
-  - call msbuild /p:Configuration=%build_config% C:\projects\obs-studio\build64\obs-studio.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
+  - call msbuild /m /p:Configuration=%build_config% C:\projects\obs-studio\build32\obs-studio.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
+  - call msbuild /m /p:Configuration=%build_config% C:\projects\obs-studio\build64\obs-studio.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
 
 before_deploy:
   - C:\projects\obs-studio\CI\before-deploy-win.cmd