Upgrade CoreCLR toolset to work on Windows (#23110)

The old package had a bug in RunCsc.cmd that didn't properly
quote the dotnet path. When the SDK is upgraded to a sufficient
version by VS, the full dotnet path will be used, which contains
spaces and fails without proper quoting. This updates us to a package
which contains almost the same compilers, but includes the fix for
quoting the dotnet path properly (in PR #23034).

build/Targets/Packages.props

@@ -51,7 +51,7 @@
     <MicrosoftNetCompilersVersion>2.6.0-beta3-62227-02</MicrosoftNetCompilersVersion>
     <MicrosoftNetRoslynDiagnosticsVersion>2.6.0-beta1-62231-02</MicrosoftNetRoslynDiagnosticsVersion>
     <MicrosoftNetCoreILAsmVersion>2.0.0</MicrosoftNetCoreILAsmVersion>
-    <MicrosoftNETCoreCompilersVersion>2.6.0-beta2-62211-02</MicrosoftNETCoreCompilersVersion>
+    <MicrosoftNETCoreCompilersVersion>2.6.0-beta3-62308-01</MicrosoftNETCoreCompilersVersion>
     <MicrosoftNETCoreVersion>5.0.0</MicrosoftNETCoreVersion>
     <MicrosoftNETCoreAppVersion>2.0.0</MicrosoftNETCoreAppVersion>
     <MicrosoftNETCorePlatformsVersion>2.0.0</MicrosoftNETCorePlatformsVersion>

build/Targets/Settings.props

@@ -57,10 +57,10 @@
     <MicrosoftCSharpRefPath>$(NuGetPackageRoot)/microsoft.csharp/$(MicrosoftCSharpVersion)/ref/netstandard1.0/</MicrosoftCSharpRefPath>
 
     <ToolsetPackagesSemaphore>$(ToolsetPackagesDir)toolsetpackages.semaphore</ToolsetPackagesSemaphore>
-    <ToolsetCompilerPackageName Condition="'$(OS)' == 'Windows_NT'">Microsoft.Net.Compilers</ToolsetCompilerPackageName>
-    <ToolsetCompilerPackageName Condition="'$(OS)' != 'Windows_NT'">Microsoft.NETCore.Compilers</ToolsetCompilerPackageName>
-    <ToolsetCompilerPackageVersion Condition="'$(OS)' == 'Windows_NT'">$(MicrosoftNetCompilersVersion)</ToolsetCompilerPackageVersion>
-    <ToolsetCompilerPackageVersion Condition="'$(OS)' != 'Windows_NT'">$(MicrosoftNETCoreCompilersVersion)</ToolsetCompilerPackageVersion>
+    <ToolsetCompilerPackageName Condition="'$(MSBuildRuntimeType)' != 'Core'">Microsoft.Net.Compilers</ToolsetCompilerPackageName>
+    <ToolsetCompilerPackageName Condition="'$(MSBuildRuntimeType)' == 'Core'">Microsoft.NETCore.Compilers</ToolsetCompilerPackageName>
+    <ToolsetCompilerPackageVersion Condition="'$(MSBuildRuntimeType)' != 'Core'">$(MicrosoftNetCompilersVersion)</ToolsetCompilerPackageVersion>
+    <ToolsetCompilerPackageVersion Condition="'$(MSBuildRuntimeType)' == 'Core'">$(MicrosoftNETCoreCompilersVersion)</ToolsetCompilerPackageVersion>
     <ToolsetCompilerPropsFilePath>$(NuGetPackageRoot)/$(ToolsetCompilerPackageName.ToLower())/$(ToolsetCompilerPackageVersion)/build/$(ToolsetCompilerPackageName).props</ToolsetCompilerPropsFilePath>
     <TargetFrameworkRootPath>$(NuGetPackageRoot)\roslyntools.referenceassemblies\$(RoslynToolsReferenceAssembliesVersion)\tools\framework</TargetFrameworkRootPath>