Fix release build

PR #8722 only had allow unsafe set in debug build, which is failing in
release. This sets allow unsafe for all configurations

src/Compilers/Test/Utilities/CSharp/CSharpCompilerTestUtilities.csproj

@@ -18,9 +18,9 @@
     <TargetFrameworkIdentifier>.NETPortable</TargetFrameworkIdentifier>
     <TargetFrameworkVersion>v5.0</TargetFrameworkVersion>
     <NoStdLib>true</NoStdLib>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' " />
   <ItemGroup>