all: const-ify str(r)chr output variables where possible

src/core/dns/nm-dns-manager.c

@@ -1510,8 +1510,8 @@ _domain_track_is_shadowed(GHashTable  *ht,
                           const char **out_parent,
                           int         *out_parent_priority)
 {
-    char *parent;
-    int   parent_priority;
+    const char *parent;
+    int         parent_priority;
 
     if (!ht)
         return FALSE;

src/core/nm-checkpoint.c

@@ -160,7 +160,7 @@ parse_connection_from_shadowed_file(const char *path, GError **error)
 {
     nm_auto_unref_keyfile GKeyFile *keyfile  = NULL;
     gs_free char                   *base_dir = NULL;
-    char                           *sep;
+    const char                     *sep;
 
     keyfile = g_key_file_new();
     if (!g_key_file_load_from_file(keyfile, path, G_KEY_FILE_NONE, error))

src/core/settings/plugins/ifcfg-rh/nms-ifcfg-rh-reader.c

@@ -77,7 +77,7 @@ get_full_file_path(const char *ifcfg_path, const char *file_path)
 {
     const char   *base    = file_path;
     gs_free char *dirname = NULL;
-    char         *p;
+    const char   *p;
 
     g_return_val_if_fail(ifcfg_path != NULL, NULL);
     g_return_val_if_fail(file_path != NULL, NULL);

src/libnm-core-aux-intern/nm-libnm-core-utils.c

@@ -483,8 +483,8 @@ nm_utils_validate_shared_dhcp_range(const char *shared_dhcp_range,
                                     GPtrArray  *addresses,
                                     GError    **error)
 {
-    char         *start_address_str;
-    char         *end_address_str;
+    const char   *start_address_str;
+    const char   *end_address_str;
     NMIPAddress  *interface_address_with_prefix;
     NMIPAddr      interface_address;
     NMIPAddr      start_address;

src/libnm-core-impl/nm-setting.c

@@ -4495,7 +4495,7 @@ nm_range_from_str(const char *str, GError **error)
     gs_free char *str_free = NULL;
     guint64       start;
     guint64       end = 0;
-    char         *c;
+    const char   *c;
 
     g_return_val_if_fail(str, NULL);
     g_return_val_if_fail(!error || !*error, NULL);