cargo-i18n: fix build with newer versions of Clang

cargo-i81n depends on the gettext-sys crate, which vendors a version of
gettext that fails to build with the default Clang in nixpkgs. Using the
packaged (“system”) gettext avoids the issue.

pkgs/by-name/ca/cargo-i18n/package.nix

@@ -1,6 +1,7 @@
 { lib
 , rustPlatform
 , fetchFromGitHub
+, gettext
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -16,6 +17,14 @@ rustPlatform.buildRustPackage rec {
 
   cargoHash = "sha256-vN62QmCuhu7AjL6xSpBU6/ul4WgNLZbjWDCFyHj6rIM=";
 
+  # Devendor gettext in the gettext-sys crate. The paths to the bin/lib/include folders have to be specified because
+  # setting `GETTEXT_SYSTEM` only works on some platforms (i.e., not Darwin).
+  env = {
+    GETTEXT_BIN_DIR = "${lib.getBin gettext}/bin";
+    GETTEXT_LIB_DIR = "${lib.getLib gettext}/lib";
+    GETTEXT_INCLUDE_DIR = "${lib.getInclude gettext}/include";
+  };
+
   cargoTestFlags = [ "--lib" ];
 
   meta = with lib; {