tree-wide: don't needlessly negate error number passed to bus_error_message()

Like it's customary in our codebase bus_error_message() internally takes
abs() of the passed error anyway, hence no need to explicitly negate it.
We mostly got this right, but in too many cases we didn't. Fix that.

src/initctl/initctl.c

@@ -115,7 +115,7 @@ static int change_runlevel(Server *s, int runlevel) {
                         NULL,
                         "ss", target, mode);
         if (r < 0)
-                return log_error_errno(r, "Failed to change runlevel: %s", bus_error_message(&error, -r));
+                return log_error_errno(r, "Failed to change runlevel: %s", bus_error_message(&error, r));
 
         return 0;
 }