shared: add NMUtilsNamedEntry

It is common to have some data indexed by a name.
If you want to sort a list of such data, you would
have to re-implement your own compare function each time.

Instead, add NMUtilsNamedEntry which as first field has
the name. So, you can create your own struct:

  struct my_data {
    const char *name;
    ... other fields
  }

and compare them with with nm_utils_named_entry_cmp().

For convenience, add another struct NMUtilsNamedValue, which
has only one data field, a pointer.

(cherry picked from commit 3adce12898)

shared/nm-utils/nm-shared-utils.h

@@ -407,6 +407,26 @@ char *nm_utils_str_utf8safe_escape_take (char *str, NMUtilsStrUtf8SafeFlags flag
 
 /*****************************************************************************/
 
+typedef struct {
+	const char *name;
+} NMUtilsNamedEntry;
+
+typedef struct {
+	union {
+		NMUtilsNamedEntry named_entry;
+		const char *name;
+	};
+	union {
+		const char *value_str;
+		gconstpointer value_ptr;
+	};
+} NMUtilsNamedValue;
+
+#define nm_utils_named_entry_cmp           nm_strcmp_p
+#define nm_utils_named_entry_cmp_with_data nm_strcmp_p_with_data
+
+/*****************************************************************************/
+
 #define NM_UTILS_NS_PER_SECOND  ((gint64) 1000000000)
 #define NM_UTILS_NS_PER_MSEC    ((gint64) 1000000)
 #define NM_UTILS_NS_TO_MSEC_CEIL(nsec)      (((nsec) + (NM_UTILS_NS_PER_MSEC - 1)) / NM_UTILS_NS_PER_MSEC)