Attempt to fix OpenSSL build under nix

Cargo.lock

@@ -3244,8 +3244,7 @@ checksum = "ff011a302c396a5197692431fc1948019154afc178baf7d8e37367442a4601cf"
 [[package]]
 name = "openssl-src"
 version = "300.2.3+3.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5cff92b6f71555b61bb9315f7c64da3ca43d87531622120fea0195fc761b4843"
+source = "git+https://github.com/link2xt/openssl-src-rs.git?branch=link2xt/copy-symlink#68efa9733ace4aae3372646838d7430b8f974c67"
 dependencies = [
  "cc",
 ]

Cargo.toml

@@ -30,6 +30,9 @@ opt-level = "z"
 codegen-units = 1
 strip = true
 
+[patch.crates-io]
+openssl-src = { git = "https://github.com/link2xt/openssl-src-rs.git", branch = "link2xt/copy-symlink" }
+
 [dependencies]
 deltachat_derive = { path = "./deltachat_derive" }
 deltachat-time = { path = "./deltachat-time" }

flake.nix

@@ -168,6 +168,9 @@
             auditable = false; # Avoid cargo-auditable failures.
             doCheck = false; # Disable test as it requires network access.
 
+            nativeBuildInputs = [
+              pkgs.perl # Needed to build vendored OpenSSL.
+            ];
             CARGO_BUILD_TARGET = rustTarget;
             TARGET_CC = "${pkgsCross.stdenv.cc}/bin/${pkgsCross.stdenv.cc.targetPrefix}cc";
             CARGO_BUILD_RUSTFLAGS = [
@@ -177,11 +180,6 @@
 
             CC = "${pkgsCross.stdenv.cc}/bin/${pkgsCross.stdenv.cc.targetPrefix}cc";
             LD = "${pkgsCross.stdenv.cc}/bin/${pkgsCross.stdenv.cc.targetPrefix}cc";
-
-            OPENSSL_LIB_DIR = "${pkgsCross.pkgsStatic.openssl.out}/lib";
-            OPENSSL_INCLUDE_DIR = "${pkgsCross.pkgsStatic.openssl.dev}/include";
-            OPENSSL_STATIC = "1";
-            OPENSSL_NO_VENDOR = "1";
           };
 
         mk-aarch64-RustPackage = mkCrossRustPackage "aarch64-unknown-linux-musl" "aarch64-unknown-linux-musl";