Use mold linker for flatpak devel

Author: ranfdev

build-aux/com.ranfdev.Geopard.Devel.json

@@ -4,7 +4,8 @@
     "runtime-version" : "42",
     "sdk" : "org.gnome.Sdk",
     "sdk-extensions" : [
-        "org.freedesktop.Sdk.Extension.rust-stable"
+        "org.freedesktop.Sdk.Extension.rust-stable",
+        "org.freedesktop.Sdk.Extension.llvm13"
     ],
     "command" : "geopard",
     "tags" : [
@@ -19,12 +20,16 @@
         "--filesystem=xdg-download/Geopard"
     ],
     "build-options" : {
-        "append-path" : "/usr/lib/sdk/rust-stable/bin",
+        "append-path": "/usr/lib/sdk/rust-stable/bin:/usr/lib/sdk/llvm13/bin",
         "build-args" : [
             "--share=network"
         ],
         "env" : {
-          "RUST_LOG": "debug"
+          "RUST_LOG": "debug",
+          "CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER": "clang",
+	  "CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS": "-C link-arg=-fuse-ld=/usr/lib/sdk/rust-stable/bin/mold",
+	  "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER": "clang",
+	  "CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_RUSTFLAGS": "-C link-arg=-fuse-ld=/usr/lib/sdk/rust-stable/bin/mold"
         }
     },
     "modules" : [