THREAD_NAME feature constant added for conditional compilation

Added the feature constant THREAD_NAME to Framework4.5 and Netstandard2.0

Author: StefanOssendorf

src/Serilog.Enrichers.Thread/Enrichers/ThreadNameEnricher.cs

@@ -12,14 +12,14 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-
+#if THREAD_NAME
 using System.Threading;
 using Serilog.Core;
 using Serilog.Events;
 
 namespace Serilog.Enrichers 
 {
-#if NET45 || NETSTANDARD2_0
+
     /// <summary>
     /// Enriches log events with a ThreadName property containing the 
     /// </summary>
@@ -44,5 +44,5 @@ public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
             }
         }
     }
-#endif
-}
+}
+#endif

src/Serilog.Enrichers.Thread/Serilog.Enrichers.Thread.csproj

@@ -28,4 +28,12 @@
     <Reference Include="Microsoft.CSharp" />
   </ItemGroup>
 
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'net45' ">
+    <DefineConstants>$(DefineConstants);THREAD_NAME</DefineConstants>
+  </PropertyGroup>
+  
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
+    <DefineConstants>$(DefineConstants);THREAD_NAME</DefineConstants>
+  </PropertyGroup>
+
 </Project>