checksyscalls: ignore fstat to silence build warning on LoongArch

fstat is replaced by statx on the new architecture, so an exception is
added to the checksyscalls script to silence the following build warning
on LoongArch:

  CALL    scripts/checksyscalls.sh
<stdin>:569:2: warning: #warning syscall fstat not implemented [-Wcpp]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Tiezhu Yang <[email protected]>
Suggested-by: WANG Xuerui <[email protected]>
Suggested-by: Arnd Bergmann <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

scripts/checksyscalls.sh

@@ -114,7 +114,6 @@ cat << EOF
 #define __IGNORE_truncate
 #define __IGNORE_stat
 #define __IGNORE_lstat
-#define __IGNORE_fstat
 #define __IGNORE_fcntl
 #define __IGNORE_fadvise64
 #define __IGNORE_newfstatat
@@ -255,6 +254,9 @@ cat << EOF
 /* 64-bit ports never needed these, and new 32-bit ports can use statx */
 #define __IGNORE_fstat64
 #define __IGNORE_fstatat64
+
+/* Newer ports are not required to provide fstat in favor of statx */
+#define __IGNORE_fstat
 EOF
 }