Fix resolving IBCMerge's path in build.cmd (dotnet#27513)

* Resolve IBCMerge's path via NuGetPackageRoot since we never actually restore ibcmerge.csproj directly.

* Additional fixes to get IBCMerge working again.

* Update src/.nuget/optdata/ibcmerge.csproj

Co-Authored-By: Elinor Fung <47805090+elinor-fung@users.noreply.github.com>

src/.nuget/optdata/ibcmerge.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.DotNet.IBCMerge" Version="$(MicrosoftDotNetIBCMergeVersion)" GeneratePathProperty="True" />
+    <PackageReference Include="Microsoft.DotNet.IBCMerge" Version="$(MicrosoftDotNetIBCMergeVersion)" />
   </ItemGroup>
 
   <!--                                                                       -->
@@ -23,10 +23,14 @@
     <!-- Error if IbcMergePackagePathOutputFile is not set. -->
     <Error Condition="'$(IbcMergePackagePathOutputFile)'==''" Text="IbcMergePackagePathOutputFile must be passed as a property." />
 
+    <PropertyGroup>
+      <IbcMergePath>$(NuGetPackageRoot)microsoft.dotnet.ibcmerge\$(MicrosoftDotNetIBCMergeVersion)</IbcMergePath>
+    </PropertyGroup>
+
     <!-- Cleanup old path file -->
     <Delete Files="$(IbcMergePackagePathOutputFile)" Condition="Exists('$(IbcMergePackagePathOutputFile)')" />
-    <WriteLinesToFile File="$(IbcMergePackagePathOutputFile)" Lines="$(PkgMicrosoft_DotNet_IBCMerge)" Overwrite="true"/>
-    <Message Text="MicrosoftDotNetIBCMergePath: $(PkgMicrosoft_DotNet_IBCMerge) written to: $(IbcMergePackagePathOutputFile)" Importance="High" />
+    <WriteLinesToFile File="$(IbcMergePackagePathOutputFile)" Lines="$(IbcMergePath)" Overwrite="true"/>
+    <Message Text="MicrosoftDotNetIBCMergePath: $(IbcMergePath) written to: $(IbcMergePackagePathOutputFile)" Importance="High" />
   </Target>
 
 </Project>

src/.nuget/optdata/optdata.csproj

@@ -72,8 +72,8 @@
     <!-- Cleanup old version file -->
     <Delete Files="$(IbcDataPackagePathOutputFile)" Condition="Exists('$(IbcDataPackagePathOutputFile)')" />
 
-    <WriteLinesToFile File="$(IbcDataPackagePathOutputFile)" Lines="$(IbcPackagePath)" Condition="Exists('$(IbcDataPackagePathOutputFile)')" Overwrite="true"/>
-    <WriteLinesToFile File="$(IbcDataPackagePathOutputFile)" Lines="" Condition="!Exists('$(IbcDataPackagePathOutputFile)')" Overwrite="true"/>
+    <WriteLinesToFile File="$(IbcDataPackagePathOutputFile)" Lines="$(IbcPackagePath)" Condition="'$(OptimizationDataSupported)' == 'True'" Overwrite="true"/>
+    <WriteLinesToFile File="$(IbcDataPackagePathOutputFile)" Lines="" Condition="'$(OptimizationDataSupported)' != 'True'" Overwrite="true"/>
     <Message Text="optimizationIBCCoreCLRVersion: $(IbcPackagePath) written to: $(IbcDataPackagePathOutputFile)" Importance="High" />
   </Target>