kernelland_emu: Added missing user_memset()

Change-Id: I703525d73572c812b1adf8b4c4805a624c3b7df7
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6839
Reviewed-by: waddlesplash <[email protected]>

src/tests/add-ons/kernel/kernelland_emu/vm.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010, Haiku Inc. All Rights Reserved.
+ * Copyright 2002-2023, Haiku Inc. All Rights Reserved.
  * Distributed under the terms of the MIT license.
  *
  * Authors:
@@ -29,6 +29,14 @@ user_strlcpy(char *to, const char *from, size_t size)
 }
 
 
+extern "C" status_t
+user_memset(void* target, char data, size_t length)
+{
+	memset(target, data, length);
+	return B_OK;
+}
+
+
 page_num_t
 vm_page_num_pages(void)
 {