[libglnx/wip/smcv/null-option-entry-ifndef] backports: Use #ifndef instead of GLIB_CHECK_VERSION

[Simon McVittie <smcv src gnome org>]

commit cdef2bb414ec05aa9bb4bf7cc15743d643eef6c3
Author: Simon McVittie <smcv collabora com>
Date:   Mon Oct 10 14:34:25 2022 +0100

    backports: Use #ifndef instead of GLIB_CHECK_VERSION
    
    As Will Thompson pointed out on !37, G_OPTION_ENTRY_NULL is a macro in
    GLib, so we can test for it with `#ifndef` rather than a version guard.
    This is a little bit nicer for parent projects that might already have
    their own backport of it.
    
    Signed-off-by: Simon McVittie <smcv collabora com>

 glnx-backports.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/glnx-backports.h b/glnx-backports.h
index d109833..0a0a9da 100644
--- a/glnx-backports.h
+++ b/glnx-backports.h
@@ -84,7 +84,7 @@ gboolean              glnx_set_object  (GObject **object_ptr,
 #define G_DBUS_METHOD_INVOCATION_UNHANDLED FALSE
 #endif
 
-#if !GLIB_CHECK_VERSION(2, 70, 0)
+#ifndef G_OPTION_ENTRY_NULL   /* added in 2.70 */
 #define G_OPTION_ENTRY_NULL { NULL, 0, 0, 0, NULL, NULL, NULL }
 #endif