log_error() if inotify_add_watch() fails

[zj: Reworded message s/to watch/to add watch on/ to make it clear
     that it was the watch init action that failed, and not the
     "process of watching". I think this way it'll be clearer to
     people who don't know what inotify does.]

src/shared/ask-password-api.c

@@ -78,6 +78,7 @@ int ask_password_tty(
                 }
 
                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
+                        log_error("Failed to add watch on %s: %m", flag_file);
                         r = -errno;
                         goto finish;
                 }

src/shared/util.c

@@ -2220,6 +2220,7 @@ int acquire_terminal(
                 wd = inotify_add_watch(notify, name, IN_CLOSE);
                 if (wd < 0) {
                         r = -errno;
+                        log_error("Failed to add watch on %s: %m", name);
                         goto fail;
                 }
         }