subtitles: make the default character set value explicit

(cherry picked from commit 78d1d1105b1b309406eca03d2275daf7e78cdd62)

modules/codec/subtitles/subsdec.c

@@ -94,7 +94,11 @@ static const char *const ppsz_encodings[] = {
 };
 
 static const char *const ppsz_encoding_names[] = {
-    N_("Auto"),
+    /* xgettext:
+      The character encoding name in parenthesis corresponds to that used for
+      the GetACP translation. "Windows-1252" applies to Western European
+      languages using the Latin alphabet. */
+    N_("Default (Windows-1252)"),
     N_("Universal (UTF-8)"),
     N_("Universal (UTF-16)"),
     N_("Universal (big endian UTF-16)"),