loongarch: Add setjmp implementation

This patch adds a setjmp implementation for LoongArch.

Signed-off-by: Zhou Yang <zhouyang@loongson.cn>
Signed-off-by: Sun Haiyong <sunhaiyong@loongson.cn>
Signed-off-by: Xiaotian Wu <wuxiaotian@loongson.cn>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

include/grub/loongarch64/setjmp.h

@@ -0,0 +1,27 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2023 Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef GRUB_SETJMP_CPU_HEADER
+#define GRUB_SETJMP_CPU_HEADER	1
+
+typedef grub_uint64_t grub_jmp_buf[12];
+
+int grub_setjmp (grub_jmp_buf env) RETURNS_TWICE;
+void grub_longjmp (grub_jmp_buf env, int val) __attribute__ ((noreturn));
+
+#endif /* ! GRUB_SETJMP_CPU_HEADER */