readline: cross-compilation fixes for iOS

readline's configure doesn't recognize *-apple-ios as supporting shared
libraries and reports "unsupported". nixpkgs' stdenv-generic adds
--disable-static by default when configure exposes that knob, so the
combination leaves Makefile with no targets and 'make all' produces
nothing. The dev/man/info/doc outputs then come up empty and the build
fails with 'failed to produce output path'.

Flip the iOS host to dontDisableStatic + --enable-static (and pass
--disable-shared explicitly to match). iOS apps ship static system libs
in practice, mirroring the ncurses iOS treatment.

Author: insipx

pkgs/development/libraries/readline/8.3.nix

@@ -90,6 +90,14 @@ stdenv.mkDerivation (finalAttrs: {
     ];
   };
 
+  # readline configure refuses shared libs on *-apple-ios; stdenv default
+  # --disable-static would then leave Makefile with no targets. iOS only.
+  dontDisableStatic = if stdenv.hostPlatform.isiOS then true else null;
+  configureFlags = lib.optionals stdenv.hostPlatform.isiOS [
+    "--enable-static"
+    "--disable-shared"
+  ];
+
   # This install error is caused by a very old libtool. We can't autoreconfHook this package,
   # so this is the best we've got!
   postInstall = lib.optionalString stdenv.hostPlatform.isOpenBSD ''