loongarch: Add support for ELF psABI v1.00 relocations

This patch adds support of the stack-based LoongArch relocations
throughout GRUB, including tools, dynamic linkage, and support for
conversion of ELF relocations into PE ones. A stack machine is required
to handle these per the spec [1] (see the R_LARCH_SOP types), of which
a simple implementation is included.

These relocations are produced by binutils 2.38 and 2.39, while the newer
v2.00 relocs require more recent toolchain (binutils 2.40+ & gcc 13+, or
LLVM 16+). GCC 13 has not been officially released as of early 2023, so
support for v1.00 relocs are expected to stay relevant for a while.

[1] https://loongson.github.io/LoongArch-Documentation/LoongArch-ELF-ABI-EN.html#_relocations

Signed-off-by: Zhou Yang <zhouyang@loongson.cn>
Signed-off-by: Xiaotian Wu <wuxiaotian@loongson.cn>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Wentao Guan <guanwentao@uniontech.com>

GRUB2/MOD_SRC/grub-2.04/util/grub-module-verifier.c

@@ -119,6 +119,32 @@ struct grub_module_verifier_arch archs[] = {
       R_AARCH64_PREL32,
       -1
     } },
+  { "loongarch64", 8, 0, EM_LOONGARCH, GRUB_MODULE_VERIFY_SUPPORTS_REL | GRUB_MODULE_VERIFY_SUPPORTS_RELA, (int[]){
+      R_LARCH_NONE,
+      R_LARCH_64,
+      R_LARCH_MARK_LA,
+      R_LARCH_SOP_PUSH_PCREL,
+      R_LARCH_SOP_PUSH_ABSOLUTE,
+      R_LARCH_SOP_PUSH_PLT_PCREL,
+      R_LARCH_SOP_SUB,
+      R_LARCH_SOP_SL,
+      R_LARCH_SOP_SR,
+      R_LARCH_SOP_ADD,
+      R_LARCH_SOP_AND,
+      R_LARCH_SOP_IF_ELSE,
+      R_LARCH_SOP_POP_32_S_10_5,
+      R_LARCH_SOP_POP_32_U_10_12,
+      R_LARCH_SOP_POP_32_S_10_12,
+      R_LARCH_SOP_POP_32_S_10_16,
+      R_LARCH_SOP_POP_32_S_10_16_S2,
+      R_LARCH_SOP_POP_32_S_5_20,
+      R_LARCH_SOP_POP_32_S_0_5_10_16_S2,
+      R_LARCH_SOP_POP_32_S_0_10_10_16_S2,
+      -1
+    }, (int[]){
+      -1
+    }
+  },
   { "mips64el", 8, 0, EM_MIPS, GRUB_MODULE_VERIFY_SUPPORTS_REL | GRUB_MODULE_VERIFY_SUPPORTS_RELA, (int[]){
       R_MIPS_64,
       R_MIPS_32,