Use Portable PDBs and turn on SourceLink

BuildToolsVersion.txt

@@ -1 +1 @@
-2.0.0-prerelease-02126-05
+2.0.0-prerelease-02127-07

Documentation/building/code-coverage.md

@@ -78,4 +78,7 @@ Some of the libraries for which contracts and tests live in the corefx repo are
 1. Follow the steps outlined at [Testing with Private CoreClr Bits](https://github.com/dotnet/corefx/blob/master/Documentation/project-docs/developer-guide.md#testing-with-private-coreclr-bits).  Make sure to include the optional steps listed as being required for code coverage.
 2. Add /p:CodeCoverageAssemblies="System.Private.CoreLib" to the previously discussed msbuild command, e.g. msbuild /t:BuildAndTest /p:Coverage=true /p:CodeCoverageAssemblies="System.Private.CoreLib"
 
+Note that you will also want to copy the System.Private.CoreLib.pdb along with the System.Private.CoreLib.dll.  As of 10/2017 this PDB must be a windows PDB (Hopefully by early 2018 OpenCOver will directly support portable PDBs.  
+You can determine if it is a windows PDB by doing 'more System.Private.CoreLib.pdb.  If it begins with 'Microsoft C/C++ MSF 7.00' it is a windows PDB)  If you need a windows PDB the Pdb2Pdb tool will convert (or you can do a msbuild /t:rebuild /p:DebugType=full in the src\mscorlib)
+
 The resulting code coverage report should now also include details for System.Private.CoreLib.

dir.props

@@ -165,6 +165,12 @@
     <BuildingUAPAOTVertical Condition="'$(BuildingUAPAOTVertical)' == '' AND ('$(_bc_TargetGroup)'=='uapaot' OR '$(BuildAllConfigurations)' == 'true')">true</BuildingUAPAOTVertical>
   </PropertyGroup>
 
+  <!-- Set the kind of PDB to Portable and turn on SourceLink (fetching source from GitHub) -->
+  <PropertyGroup>
+    <DebugType Condition="'$(DebugType)' == ''">Portable</DebugType>
+    <UseSourceLink>true</UseSourceLink>
+  </PropertyGroup>
+
   <!-- Set up Default symbol and optimization for Configuration -->
   <Choose>
     <When Condition="'$(ConfigurationGroup)'=='Debug'">