tree-wide: drop workarounds for statx()

struct statx in glibc header was introduced in glibc-2.28
(fd70af45528d59a00eb3190ef6706cb299488fcd), but at that time,
sys/stat.h conflicts with linux/stat.h. Since glibc-2.30
(5dad6ffbb2b76215cfcd38c3001778536ada8e8a), sys/stat.h includes
linux/stat.h if exists.

Since now our baseline of glibc is 2.31. Hence, we can drop workarounds
for struct statx by importing linux/stat.h from newer kernel (v6.14-rc4).

src/basic/dirent-util.c

@@ -9,7 +9,7 @@
 #include "string-util.h"
 
 int dirent_ensure_type(int dir_fd, struct dirent *de) {
-        STRUCT_STATX_DEFINE(sx);
+        struct statx sx;
         int r;
 
         assert(dir_fd >= 0);