only use fstatat and others legacy stat syscalls if they exist

riscv32 and future architectures only provide statx.

src/stat/fstatat.c

@@ -6,7 +6,6 @@
 #include <stdint.h>
 #include <sys/sysmacros.h>
 #include "syscall.h"
-#include "kstat.h"
 
 struct statx {
 	uint32_t stx_mask;
@@ -69,6 +68,10 @@ static int fstatat_statx(int fd, const char *restrict path, struct stat *restric
 	return 0;
 }
 
+#ifdef SYS_fstatat
+
+#include "kstat.h"
+
 static int fstatat_kstat(int fd, const char *restrict path, struct stat *restrict st, int flag)
 {
 	int ret;
@@ -130,15 +133,20 @@ static int fstatat_kstat(int fd, const char *restrict path, struct stat *restric
 
 	return 0;
 }
+#endif
 
 int __fstatat(int fd, const char *restrict path, struct stat *restrict st, int flag)
 {
 	int ret;
+#ifdef SYS_fstatat
 	if (sizeof((struct kstat){0}.st_atime_sec) < sizeof(time_t)) {
 		ret = fstatat_statx(fd, path, st, flag);
 		if (ret!=-ENOSYS) return __syscall_ret(ret);
 	}
 	ret = fstatat_kstat(fd, path, st, flag);
+#else
+	ret = fstatat_statx(fd, path, st, flag);
+#endif
 	return __syscall_ret(ret);
 }