nix: use symlinks for maven dependencies derivation

This should reduce the size of the derivation by >50%.

Signed-off-by: Jakub Sokołowski <jakub@status.im>

nix/mobile/android/maven-and-npm-deps/maven/default.nix

@@ -9,10 +9,9 @@ let
   mavenSourceFiles =
     let
       srcs = import ./maven-sources.nix { };
-      system = if stdenv.isDarwin then "osx" else "linux";
       # Warning: This must be the same as gradlePluginVersion android/gradle.properties
       version = "3.5.3-5435860";
-      aapt2NativePkg = "https://dl.google.com/dl/android/maven2/com/android/tools/build/aapt2/${version}/aapt2-${version}-${system}";
+      aapt2NativePkg = "https://dl.google.com/dl/android/maven2/com/android/tools/build/aapt2/${version}/aapt2-${version}-linux";
     in srcs // (if !stdenv.isLinux then { } else {
       # On Linux, we need to patch the interpreter in Java packages that contain native executables to use Nix's interpreter instead
       "${aapt2NativePkg}" = srcs."${aapt2NativePkg}" // {

nix/tools/maven/maven-repo-builder.nix

@@ -40,13 +40,13 @@ let
         mkdir -p ${directory}
 
         ${optionalString (pom-download != "") ''
-        cp -f "${pom-download}" "${getPOM dep.path}"
+        ln -s "${pom-download}" "${getPOM dep.path}"
         ''}
         ${optionalString (pom.sha1 != "") ''
         echo "${pom.sha1}" > "${getPOM dep.path}.sha1"
         ''}
         ${optionalString (jar-download != "") ''
-        cp -f "${jar-download}" "${dep.path}.${dep.type}"
+        ln -s "${jar-download}" "${dep.path}.${dep.type}"
         ''}
         ${optionalString (jar.sha1 != "") ''
         echo "${jar.sha1}" > "${dep.path}.${dep.type}.sha1"
@@ -54,6 +54,9 @@ let
         
         ${if dep.postCopy != "" then ''
           depPath="$PWD/${dep.path}"
+          # postCopy can't modify the jar if it's a symlink
+          rm "${dep.path}.${dep.type}"
+          cp "${jar-download}" "${dep.path}.${dep.type}"
           ${dep.postCopy}
           unset depPath
         '' else ""