tree-wide: when %m is used in log_*, always specify errno explicitly

All those uses were correct, but I think it's better to be explicit.
Using implicit errno is too error prone, and with this change we can require
(in the sense of a style guideline) that the code is always specified.

Helpful query: git grep -n -P 'log_[^s][a-z]+\(.*%m'

src/tmpfiles/tmpfiles.c

@@ -724,10 +724,9 @@ static int path_set_xattrs(Item *i, const char *path) {
 
                 n = strlen(*value);
                 log_debug("Setting extended attribute '%s=%s' on %s.", *name, *value, path);
-                if (lsetxattr(path, *name, *value, n, 0) < 0) {
-                        log_error("Setting extended attribute %s=%s on %s failed: %m", *name, *value, path);
-                        return -errno;
-                }
+                if (lsetxattr(path, *name, *value, n, 0) < 0)
+                        return log_error_errno(errno, "Setting extended attribute %s=%s on %s failed: %m",
+                                               *name, *value, path);
         }
         return 0;
 }