Splitting out UEFI bootloader code from kernel

Now the bootloader should be responsible for all initial setup,
loading the kernel, and then handing off to the kernel with
proper data in place.

src/arch/x86_64/boot.s

@@ -0,0 +1,12 @@
+; boot.s -- Kernel start location.
+
+[BITS 64]
+ALIGN 4
+
+SECTION .text
+[GLOBAL start]
+
+start:
+	; Load multiboot header location
+	mov ebx, 0xdeadbeef
+	jmp $