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/boot/utility.h

@@ -0,0 +1,20 @@
+#include <efi.h>
+#include <efilib.h>
+#include "console.h"
+
+#define UNUSED __attribute__((unused))
+
+const CHAR16 *util_error_message(EFI_STATUS status);
+
+#define CHECK_EFI_STATUS_OR_RETURN(s, msg, ...)   \
+	if (EFI_ERROR((s))) { \
+		Print(L"EFI_ERROR: " msg L": %s\n", ## __VA_ARGS__, util_error_message(s)); \
+		return (s); \
+	}
+
+#define CHECK_EFI_STATUS_OR_FAIL(s)   \
+	if (EFI_ERROR((s))) { \
+		con_status_fail(util_error_message(s)); \
+		while (1) __asm__("hlt"); \
+	}
+