stat-util: provide single fallback implementation of statx()

This simplifies things quite a bit, and is reusable wherever we want to
use statx() later on. Not sure why I didn't do it like this right from
the beginning...

src/basic/missing_stat.h

@@ -49,6 +49,16 @@ struct statx STATX_DEFINITION;
  * defines an older definition */
 struct new_statx STATX_DEFINITION;
 
+/* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
+#ifndef AT_STATX_SYNC_AS_STAT
+#define AT_STATX_SYNC_AS_STAT 0x0000
+#endif
+
+/* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
+#ifndef AT_STATX_FORCE_SYNC
+#define AT_STATX_FORCE_SYNC 0x2000
+#endif
+
 /* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
 #ifndef AT_STATX_DONT_SYNC
 #define AT_STATX_DONT_SYNC 0x4000
@@ -64,11 +74,21 @@ struct new_statx STATX_DEFINITION;
 #define STATX_MODE 0x00000002U
 #endif
 
+/* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
+#ifndef STATX_NLINK
+#define STATX_NLINK 0x00000004U
+#endif
+
 /* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
 #ifndef STATX_UID
 #define STATX_UID 0x00000008U
 #endif
 
+/* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
+#ifndef STATX_GID
+#define STATX_GID 0x00000010U
+#endif
+
 /* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
 #ifndef STATX_ATIME
 #define STATX_ATIME 0x00000020U
@@ -89,6 +109,16 @@ struct new_statx STATX_DEFINITION;
 #define STATX_INO 0x00000100U
 #endif
 
+/* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
+#ifndef STATX_SIZE
+#define STATX_SIZE 0x00000200U
+#endif
+
+/* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
+#ifndef STATX_BLOCKS
+#define STATX_BLOCKS 0x00000400U
+#endif
+
 /* a528d35e8bfcc521d7cb70aaf03e1bd296c8493f (4.11) */
 #ifndef STATX_BTIME
 #define STATX_BTIME 0x00000800U