darwin/error: add partial l10n and doc

po/POTFILES.in

@@ -74,6 +74,7 @@ src/config/file.c
 src/config/help.c
 src/config/intf.c
 src/config/keys.c
+src/darwin/error.c
 src/extras/libc.c
 src/extras/tdestroy.c
 src/input/access.c

src/darwin/error.c

@@ -30,14 +30,14 @@
 
 const char *vlc_strerror_c(int errnum)
 {
-    /* C run-time errors */
+    /* We cannot simply use strerror() here, since it is not thread-safe. */
     if ((unsigned)errnum < (unsigned)sys_nerr)
         return sys_errlist[errnum];
 
-    return "Unknown error";
+    return _("Unknown error");
 }
 
 const char *vlc_strerror(int errnum)
 {
-    return vlc_gettext(vlc_strerror_c(errnum));
+    return vlc_strerror_c(errnum);
 }