x86: added missing panic function

cpu/x86/panic.c

@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2015 INRIA
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup x86_cpu
+ * @{
+ *
+ * @file
+ * @brief       Crash handling functions implementation for x86 port
+ *
+ * @author      Oliver Hahm <oliver.hahm@inria.fr>
+ */
+
+#include "x86_reboot.h"
+#include "lpm.h"
+
+void panic_arch(void)
+{
+#if DEVELHELP
+    /* enter infinite loop, into deepest possible sleep mode */
+    while (1) {
+        lpm_set(LPM_OFF);
+    }
+#else
+    x86_shutdown();
+#endif
+}