xz: Translate also the string used to print the program name.

French needs a space before a colon, e.g. "xz : foo error".

src/xz/message.c

@@ -726,7 +726,11 @@ vmessage(enum message_verbosity v, const char *fmt, va_list ap)
 
 		progress_flush(false);
 
-		fprintf(stderr, "%s: ", progname);
+		// TRANSLATORS: This is the program name in the beginning
+		// of the line in messages. Usually it becomes "xz: ".
+		// This is a translatable string because French needs
+		// a space before a colon.
+		fprintf(stderr, _("%s: "), progname);
 		vfprintf(stderr, fmt, ap);
 		fputc('\n', stderr);