* mark units compiled with cs_compilesystem with a corresponding flag

compiler/fppu.pas

@@ -1028,6 +1028,8 @@ var
           include(moduleflags,mf_local_symtable);
         if cs_checkpointer_called in current_settings.moduleswitches then
           include(moduleflags,mf_checkpointer_called);
+        if cs_compilesystem in current_settings.moduleswitches then
+          include(moduleflags,mf_system_unit);
 {$ifdef i8086}
         if current_settings.x86memorymodel in [mm_medium,mm_large,mm_huge] then
           include(moduleflags,mf_i8086_far_code);

compiler/globtype.pas

@@ -416,7 +416,8 @@ interface
          mf_wasm_bf_exceptions,       { unit was compiled in WebAssembly 'branchful' exceptions mode }
          mf_wasm_js_exceptions,       { unit was compiled in WebAssembly JavaScript-based exceptions mode }
          mf_wasm_native_exceptions,   { unit was compiled in WebAssembly native exceptions mode }
-         mf_wasm_threads              { unit was compiled with WebAssembly multithreading support turned on }
+         mf_wasm_threads,             { unit was compiled with WebAssembly multithreading support turned on }
+         mf_system_unit               { unit was compiled as a System unit }
        );
        tmoduleflags = set of tmoduleflag;