boot,shared: share the definitions of EFI_LOADER_FEATURE macros

This means the the code needs to be kept compatible in the shared header,
but I think that still nicer than having two places to declare the same
things.

I added src/boot to -I, so that efi/foo.h needs to be used. This reduces
the potential for accidentally including the wrong header.

src/boot/efi/boot.c

@@ -9,6 +9,7 @@
 #include "disk.h"
 #include "graphics.h"
 #include "linux.h"
+#include "loader-features.h"
 #include "measure.h"
 #include "pe.h"
 #include "shim.h"
@@ -2277,11 +2278,11 @@ static VOID config_write_entries_to_variable(Config *config) {
 
 EFI_STATUS efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *sys_table) {
         static const UINT64 loader_features =
-                (1ULL << 0) | /* I honour the LoaderConfigTimeout variable */
-                (1ULL << 1) | /* I honour the LoaderConfigTimeoutOneShot variable */
-                (1ULL << 2) | /* I honour the LoaderEntryDefault variable */
-                (1ULL << 3) | /* I honour the LoaderEntryOneShot variable */
-                (1ULL << 4) | /* I support boot counting */
+                EFI_LOADER_FEATURE_CONFIG_TIMEOUT |
+                EFI_LOADER_FEATURE_CONFIG_TIMEOUT_ONE_SHOT |
+                EFI_LOADER_FEATURE_ENTRY_DEFAULT |
+                EFI_LOADER_FEATURE_ENTRY_ONESHOT |
+                EFI_LOADER_FEATURE_BOOT_COUNTING |
                 0;
 
         _cleanup_freepool_ CHAR16 *infostr = NULL, *typestr = NULL;

src/boot/efi/loader-features.h

@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+#pragma once
+
+#ifndef UINT64_C
+#  define UINT64_C(c) (c ## ULL)
+#endif
+
+#define EFI_LOADER_FEATURE_CONFIG_TIMEOUT          (UINT64_C(1) << 0)
+#define EFI_LOADER_FEATURE_CONFIG_TIMEOUT_ONE_SHOT (UINT64_C(1) << 1)
+#define EFI_LOADER_FEATURE_ENTRY_DEFAULT           (UINT64_C(1) << 2)
+#define EFI_LOADER_FEATURE_ENTRY_ONESHOT           (UINT64_C(1) << 3)
+#define EFI_LOADER_FEATURE_BOOT_COUNTING           (UINT64_C(1) << 4)
+#define EFI_LOADER_FEATURE_XBOOTLDR                (UINT64_C(1) << 5)