Partial backport of the scripts/glibcelf.py part of:

commit 2d83247d90c9f0bfee7f3f2505bc1b13b6f36c04
Author: caiyinyu <caiyinyu@loongson.cn>
Date:   Tue Jul 19 09:20:45 2022 +0800

    LoongArch: Add relocations and ELF flags to elf.h and scripts/glibcelf.py

diff --git a/scripts/glibcelf.py b/scripts/glibcelf.py
index 47f95d07baefb4ae..de0509130ed9ad47 100644
--- a/scripts/glibcelf.py
+++ b/scripts/glibcelf.py
@@ -252,7 +252,8 @@ class Machine(_OpenIntEnum):
     EM_RISCV = 243
     EM_BPF = 247
     EM_CSKY = 252
-    EM_NUM = 253
+    EM_LOONGARCH = 258
+    EM_NUM = 259
     EM_ALPHA = 0x9026
 
 class Et(_OpenIntEnum):