um: Mark install_fatal_handler as __init

It's only invoked during boot from main().

Signed-off-by: Tiwei Bie <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Johannes Berg <[email protected]>

Author: btw616

arch/um/os-Linux/main.c

@@ -48,7 +48,7 @@ static void last_ditch_exit(int sig)
 	exit(1);
 }
 
-static void install_fatal_handler(int sig)
+static void __init install_fatal_handler(int sig)
 {
 	struct sigaction action;