Ignore generated file kernel/x509_certificate_list

$ git status
# On branch pending-rebases
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#	kernel/x509_certificate_list
nothing added to commit but untracked files present (use "git add" to track)
$
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

kernel/.gitignore

@@ -5,3 +5,4 @@ config_data.h
 config_data.gz
 timeconst.h
 hz.bc
+x509_certificate_list