[libc][NFC] Use no_sanitize("all")

This function cannot have any instrumentation because it's
assembly must match exactly what the debugger is expecting.

Previously it was just a list of what sanitizers we expect
libc would be sanitized with but this is untenable.

libc/src/signal/linux/__restore.cpp

@@ -16,7 +16,7 @@
 namespace __llvm_libc {
 
 extern "C" void __restore_rt()
-    __attribute__((no_sanitize("thread", "memory", "undefined", "fuzzer"),
+    __attribute__((no_sanitize("all"),
                    hidden));
 
 extern "C" void __restore_rt() { __llvm_libc::syscall(SYS_rt_sigreturn); }