x86_64: generate a seed for the RNG with RDRAND when available

arch/x86_64/include/kernel/machine/random.h

@@ -0,0 +1,10 @@
+#ifndef KERNEL_X86_64_RANDOM_H_
+#define KERNEL_X86_64_RANDOM_H_
+
+#include <stdbool.h>
+#include <stdint.h>
+
+extern bool ml_hwrng_available(void);
+extern uint64_t ml_hwrng_generate(void);
+
+#endif