Add support for source-build (#1740)

src/Logging/Logging.AzureAppServices/Directory.Build.props

@@ -0,0 +1,8 @@
+<Project>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory)..\, Directory.Build.props))\Directory.Build.props" />
+
+  <PropertyGroup>
+    <!-- These projects depend on a 3rd party source -->
+    <ExcludeFromSourceBuild>true</ExcludeFromSourceBuild>
+  </PropertyGroup>
+</Project>

src/Logging/Logging.Testing/src/Microsoft.Extensions.Logging.Testing.csproj

@@ -10,6 +10,7 @@
     <!-- This is an internal package for testing purposes only. -->
     <IsPackable>true</IsPackable>
     <IsShipping>false</IsShipping>
+    <ExcludeFromSourceBuild>true</ExcludeFromSourceBuild>
   </PropertyGroup>
 
   <ItemGroup>