perf kvm: Fix debug assertion

There are 2 slots left for kvm_add_default_arch_event, fix the
assertion so that debug builds don't fail the assert and to agree with
the comment.

Fixes: 45ff39f6e70aa55d0 ("perf tools kvm: Fix the potential out of range memory access issue")
Signed-off-by: Ian Rogers <[e-mail]>
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/builtin-kvm.c

···
 	for (j = 1; j < argc; j++, i++)
 		rec_argv[i] = STRDUP_FAIL_EXIT(argv[j]);
 
-	BUG_ON(i != rec_argc);
+	BUG_ON(i + 2 != rec_argc);
 
 	ret = kvm_add_default_arch_event(&i, rec_argv);
 	if (ret)