apply.c: remove unnecessary include

Remove include "lockfile.h" from builtin/apply.c, which is orphaned
since 6d058c8826 (apply: move lockfile into `apply_state`, 2017-10-05)

Signed-off-by: Garrit Franke <garrit@slashdev.space>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/apply.c

@@ -1,7 +1,6 @@
 #include "cache.h"
 #include "builtin.h"
 #include "parse-options.h"
-#include "lockfile.h"
 #include "apply.h"
 
 static const char * const apply_usage[] = {