Move CompareInfo.cs to shared corelib partition (dotnet/coreclr#14407)

Signed-off-by: dotnet-bot-corefx-mirror <dotnet-bot@microsoft.com>

Author: jkotas

src/Common/src/CoreLib/System.Private.CoreLib.Shared.projitems

@@ -115,6 +115,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendarWeekRule.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CalendricalCalculationsHelper.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\ChineseLunisolarCalendar.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CompareInfo.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureNotFoundException.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\CultureTypes.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\DateTimeFormat.cs" />