All: Fix crash when attempting to hook function on older OS builds

`RtlQueryFeatureConfiguration` is not available on old Windows 10
builds, like 17763 (LTSC 2019).
Related issue: https://github.com/valinet/ExplorerPatcher/discussions/1142

ExplorerPatcher/dllmain.c

@@ -10161,6 +10161,7 @@ DWORD Inject(BOOL bIsExplorer)
     }
 
     RtlQueryFeatureConfigurationFunc = GetProcAddress(GetModuleHandleW(L"ntdll.dll"), "RtlQueryFeatureConfiguration");
+    if (RtlQueryFeatureConfigurationFunc) {
         rv = funchook_prepare(
             funchook,
             (void**)&RtlQueryFeatureConfigurationFunc,
@@ -10171,6 +10172,7 @@ DWORD Inject(BOOL bIsExplorer)
             FreeLibraryAndExitThread(hModule, rv);
             return FALSE;
         }
+    }
     printf("Setup ntdll functions done\n");