musl: add several missing statx macros

glibc's sys/stat.h includes linux/stat.h, and we have copy of it from
the latest kernel, hence all new flags are always defined.
However, musl's sys/stat.h does not include linux/stat.h, and moreover,
they conflict with each other, hence we cannot include both header
simultaneously. Let's define missing macros to support musl.

src/include/musl/sys/stat.h

@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include_next <sys/stat.h>
+
+#include <assert.h>
+#include <stddef.h>
+
+/* musl's sys/stat.h does not include linux/stat.h, and unfortunately they conflict with each other.
+ * Hence, some relatively new macros need to be explicitly defined here. */
+
+/* Before 23ab04a8630225371455d5f4538fd078665bb646, statx.stx_mnt_id is not defined. */
+#ifndef STATX_MNT_ID
+static_assert(offsetof(struct statx, __pad1) == offsetof(struct statx, stx_dev_minor) + sizeof(uint32_t), "");
+#define stx_mnt_id __pad1[0]
+#endif
+
+#ifndef STATX_MNT_ID
+#define STATX_MNT_ID            0x00001000U
+#endif
+#ifndef STATX_DIOALIGN
+#define STATX_DIOALIGN          0x00002000U
+#endif
+#ifndef STATX_MNT_ID_UNIQUE
+#define STATX_MNT_ID_UNIQUE     0x00004000U
+#endif
+#ifndef STATX_SUBVOL
+#define STATX_SUBVOL            0x00008000U
+#endif
+#ifndef STATX_WRITE_ATOMIC
+#define STATX_WRITE_ATOMIC      0x00010000U
+#endif
+#ifndef STATX_DIO_READ_ALIGN
+#define STATX_DIO_READ_ALIGN    0x00020000U
+#endif
+
+#ifndef STATX_ATTR_COMPRESSED
+#define STATX_ATTR_COMPRESSED   0x00000004
+#endif
+#ifndef STATX_ATTR_IMMUTABLE
+#define STATX_ATTR_IMMUTABLE    0x00000010
+#endif
+#ifndef STATX_ATTR_APPEND
+#define STATX_ATTR_APPEND       0x00000020
+#endif
+#ifndef STATX_ATTR_NODUMP
+#define STATX_ATTR_NODUMP       0x00000040
+#endif
+#ifndef STATX_ATTR_ENCRYPTED
+#define STATX_ATTR_ENCRYPTED    0x00000800
+#endif
+#ifndef STATX_ATTR_AUTOMOUNT
+#define STATX_ATTR_AUTOMOUNT    0x00001000
+#endif
+#ifndef STATX_ATTR_MOUNT_ROOT
+#define STATX_ATTR_MOUNT_ROOT   0x00002000
+#endif
+#ifndef STATX_ATTR_VERITY
+#define STATX_ATTR_VERITY       0x00100000
+#endif
+#ifndef STATX_ATTR_DAX
+#define STATX_ATTR_DAX          0x00200000
+#endif
+#ifndef STATX_ATTR_WRITE_ATOMIC
+#define STATX_ATTR_WRITE_ATOMIC 0x00400000
+#endif