Add platform as a default constant

Author: Lamparter

Directory.Build.props

@@ -7,9 +7,9 @@
         <RuntimeIdentifiers>win-x86;win-x64;win-arm64</RuntimeIdentifiers>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
         <Nullable>enable</Nullable>
-        <DefineConstants Condition="'$(Configuration)' == 'Debug'">$(DefineConstants);TRACE;DEBUG;NETFX_CORE</DefineConstants>
-        <DefineConstants Condition="'$(Configuration)' != 'Debug'">$(DefineConstants);TRACE;RELEASE;NETFX_CORE</DefineConstants>
+        <DefineConstants Condition="'$(Configuration)' == 'Debug'">$(DefineConstants);$(Platform);TRACE;DEBUG;NETFX_CORE</DefineConstants>
+        <DefineConstants Condition="'$(Configuration)' != 'Debug'">$(DefineConstants);$(Platform);TRACE;RELEASE;NETFX_CORE</DefineConstants>
         <Optimize Condition="'$(Configuration)' != 'Debug'">true</Optimize>
     </PropertyGroup>
 
-</Project>
+</Project>