ci: reduce AppVeyor workload

Don't compile with VS2013 if VS2015 compilation fails.
Build only SSE2 and AVX2 GSdx variants.

appveyor.yml

@@ -6,13 +6,16 @@ version: 1.{build}-{branch}
 environment:
   matrix:
   - platform: Win32
-    target: ReleaseAll
+    target: AppVeyor
     visualstudio_string: vs2015
   - platform: Win32
     VisualStudioVersion: 12.0
-    target: ReleaseAll
+    target: AppVeyor
     visualstudio_string: vs2013
 
+matrix:
+  fast_finish: true
+
 init:
 # Use CRLF line endings on Windows so users can just use Notepad.
   - git config --global core.autocrlf true

buildbot.xml

@@ -40,7 +40,7 @@
     </ItemGroup>
     <Delete Files="@(CruftToDelete)" />
   </Target>
-  <Target Name="InternalBuild" AfterTargets="DebugAll;DevelAll;ReleaseAll">
+  <Target Name="InternalBuild" AfterTargets="DebugAll;DevelAll;ReleaseAll;AppVeyor">
     <MSBuild Projects="@(SolutionSet)" BuildInParallel="false" Properties="Configuration=$(BaseConfiguration)" Targets="Clean" />
     <MSBuild Projects="@(ProjectSetCPU)" BuildInParallel="false" Properties="Configuration=%(ConfigCPU.Identity)" Targets="Clean" />
     <CallTarget Targets="CleanCruft" />
@@ -73,4 +73,12 @@
       <ConfigCPU Include="Release AVX;Release AVX2;Release SSE4;Release SSSE3"/>
     </ItemGroup>
   </Target>
+  <Target Name="AppVeyor">
+    <PropertyGroup>
+      <BaseConfiguration>Release</BaseConfiguration>
+    </PropertyGroup>
+    <ItemGroup>
+      <ConfigCPU Include="Release AVX2"/>
+    </ItemGroup>
+  </Target>
 </Project>