+/* If this changes, userland unwinders that Know Things about our signal
+ frame will break. Do not undertake lightly. It also implies an ABI
+ change wrt the size of siginfo_t, which may cause some pain. */
+extern char compile_time_assert
+ [offsetof(struct rt_sigframe, uc.uc_mcontext) == 176 ? 1 : -1];
+