Enable linking groups for the parser on Linux

The previous fix didn't work at all because premake's syntax is extremely strange at best and without any sense whatsoever it completely failed before I moved the linking groups just a few lines up.

Signed-off-by: Dimitar Dobrev <dpldobrev@protonmail.com>

src/CppParser/premake5.lua

@@ -15,6 +15,10 @@ project "CppSharp.CppParser"
   SetupNativeProject()
   rtti "Off"
   defines { "DLL_EXPORT" }
+  
+  if os.istarget("linux") then
+    linkgroups "On"
+  end
 
   filter "action:vs*"
     buildoptions { clang_msvc_flags }
@@ -22,10 +26,6 @@ project "CppSharp.CppParser"
   if os.getenv("APPVEYOR") then
     linkoptions { "/ignore:4099" } -- LNK4099: linking object as if no debug info
   end
-  
-  if os.istarget("linux") then
-    linkgroups "On"
-  end
 
   filter {}