misc: Add missing DefineConstants definition in Ryujinx.Common

Fix flathub and nixpkgs build hopefully now.

Ryujinx.Common/Ryujinx.Common.csproj

@@ -3,6 +3,7 @@
   <PropertyGroup>
     <TargetFramework>net7.0</TargetFramework>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <DefineConstants Condition=" '$(ExtraDefineConstants)' != '' ">$(DefineConstants);$(ExtraDefineConstants)</DefineConstants>
   </PropertyGroup>
 
   <ItemGroup>