removed lto flag for workaround of V/M isa ext dep

flake.nix

@@ -10,7 +10,7 @@
     pkgs = import nixpkgs {
       system = "x86_64-linux";
     };
-    riscv32Pkgs = import nixpkgs {
+    riscvPkgs = import nixpkgs {
       system = "x86_64-linux";
       crossSystem = {
         system = "riscv32-none-elf";
@@ -43,6 +43,7 @@
         sed -i 's/PREFIX_DEFAULT:=riscv64-elf/PREFIX_DEFAULT:=riscv32-unknown-none-elf/' $out/src/ch32fun/ch32fun.mk
         sed -i 's/MINICHLINK?=$(CH32FUN)\/..\/minichlink/MINICHLINK?=$(CH32FUN)\/..\/..\/bin/' $out/src/ch32fun/ch32fun.mk
         sed -i 's/GENERATED_LD_FILE:=$(CH32FUN)\/generated_$(TARGET_MCU_PACKAGE)_$(TARGET_MCU_MEMORY_SPLIT).ld/GENERATED_LD_FILE:=.\/generated_$(TARGET_MCU_PACKAGE)_$(TARGET_MCU_MEMORY_SPLIT).ld/' $out/src/ch32fun/ch32fun.mk
+        sed -i 's/-flto//' $out/src/ch32fun/ch32fun.mk
 
         mkdir -p $out/{bin,lib}
         mkdir -p $out/lib/udev/rules.d
@@ -69,7 +70,7 @@
       echo "${ch32fun}/src/ch32fun"
     '';
 
-    shellProfile = riscv32Pkgs.mkShell {
+    shellProfile = riscvPkgs.mkShell {
       name = "WCH ch32";
       packages = [
         pkgs.wlink