bootctl: print SystemdOptions from efivarfs if newer than our cache

The logic is that if the options are updated after boot, we *don't* use
the new value. But we still want to print out the changed contents in
bootctl as to not confuse people.

Fixes #19597.
Also https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=988450.

$ build/bootctl systemd-efi-options
quiet
Note: SystemdOptions EFI variable has been modified since boot. New value: debug

The hint is printed to stderr, so scripts should not be confused.

src/basic/efivars.h

@@ -52,6 +52,7 @@ bool is_efi_secure_boot_setup_mode(void);
 
 int cache_efi_options_variable(void);
 int systemd_efi_options_variable(char **line);
+int systemd_efi_options_efivarfs_if_newer(char **line);
 
 #else
 
@@ -90,4 +91,8 @@ static inline int cache_efi_options_variable(void) {
 static inline int systemd_efi_options_variable(char **line) {
         return -ENODATA;
 }
+
+static inline int systemd_efi_options_efivarfs_if_newer(char **line) {
+        return -ENODATA;
+}
 #endif