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/stat-util.h

@@ -11,7 +11,6 @@
 
 #include "fs-util.h"
 #include "macro.h"
-#include "missing_stat.h"
 #include "siphash24.h"
 #include "time-util.h"
 
@@ -90,31 +89,12 @@ bool stat_inode_same(const struct stat *a, const struct stat *b);
 bool stat_inode_unmodified(const struct stat *a, const struct stat *b);
 
 bool statx_inode_same(const struct statx *a, const struct statx *b);
-bool statx_mount_same(const struct new_statx *a, const struct new_statx *b);
+bool statx_mount_same(const struct statx *a, const struct statx *b);
 
 int statx_fallback(int dfd, const char *path, int flags, unsigned mask, struct statx *sx);
 
 int xstatfsat(int dir_fd, const char *path, struct statfs *ret);
 
-#if HAS_FEATURE_MEMORY_SANITIZER
-#  warning "Explicitly initializing struct statx, to work around msan limitation. Please remove as soon as msan has been updated to not require this."
-#  define STRUCT_STATX_DEFINE(var)              \
-        struct statx var = {}
-#  define STRUCT_NEW_STATX_DEFINE(var)          \
-        union {                                 \
-                struct statx sx;                \
-                struct new_statx nsx;           \
-        } var = {}
-#else
-#  define STRUCT_STATX_DEFINE(var)              \
-        struct statx var
-#  define STRUCT_NEW_STATX_DEFINE(var)          \
-        union {                                 \
-                struct statx sx;                \
-                struct new_statx nsx;           \
-        } var
-#endif
-
 static inline usec_t statx_timestamp_load(const struct statx_timestamp *ts) {
         return timespec_load(&(const struct timespec) { .tv_sec = ts->tv_sec, .tv_nsec = ts->tv_nsec });
 }
@@ -140,6 +120,3 @@ static inline bool stat_is_set(const struct stat *st) {
 static inline bool statx_is_set(const struct statx *sx) {
         return sx && sx->stx_mask != 0;
 }
-static inline bool new_statx_is_set(const struct new_statx *sx) {
-        return sx && sx->stx_mask != 0;
-}