try align with fsc.fsproj

Author: dsyme

src/fsharp/fsi/fsi.fsproj

@@ -35,9 +35,9 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\FSharp.Core\FSharp.Core.fsproj" />
-    <ProjectReference Include="..\FSharp.Compiler.Private\FSharp.Compiler.Private.fsproj" />
-    <ProjectReference Include="..\FSharp.Compiler.Interactive.Settings\FSharp.Compiler.Interactive.Settings.fsproj" />
+    <ProjectReference Include="$(MSBuildThisFileDirectory)..\FSharp.Core\FSharp.Core.fsproj" />
+    <ProjectReference Include="$(MSBuildThisFileDirectory)..\FSharp.Compiler.Private\FSharp.Compiler.Private.fsproj" />
+    <ProjectReference Include="$(MSBuildThisFileDirectory)..\FSharp.Compiler.Interactive.Settings\FSharp.Compiler.Interactive.Settings.fsproj" />
 
     <!-- only used when '$(TargetFramework)' == 'netstandard2.0' -->
     <ProjectReference Include="..\FSharp.Build\FSharp.Build.fsproj" Condition="'$(TargetFramework)' == 'netstandard2.0'" />
@@ -48,7 +48,7 @@
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net46'">
     <!-- only used when '$(TargetFramework)' == 'net472' -->
-    <ProjectReference Include="..\FSharp.Compiler.Server.Shared\FSharp.Compiler.Server.Shared.fsproj" Condition="'$(TargetFramework)' == 'net472'" />
+    <ProjectReference Include="$(MSBuildThisFileDirectory)..\FSharp.Compiler.Server.Shared\FSharp.Compiler.Server.Shared.fsproj" Condition="'$(TargetFramework)' == 'net472'" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFramework)' == 'net472'">