fix(qr): rewrite 7 failing language tests to use native C FFI

All use dlopen/dlsym to libqrencode.so (system-wide via gcc role):
- Haskell: System.Posix.DynamicLinker + foreign import ccall "dynamic"
- F#: Mono P/Invoke DllImport("libqrencode.so")
- COBOL: LINKAGE SECTION for proper struct pointer access
- Nim: dynlib module (loadLib/symAddr)
- Fortran: renamed dlclose binding to avoid symbol collision
- D: core.sys.posix.dlfcn (dlopen/dlsym)
- OCaml: Ctypes.foreign via ocamlfind #require

test/qr.ml

@@ -1,4 +1,27 @@
+#use "topfind";;
+#require "ctypes";;
+#require "ctypes.foreign";;
+
+open Ctypes;;
+open Foreign;;
+
+type qrcode
+let qrcode : qrcode structure typ = structure "QRcode";;
+let _qr_version = field qrcode "version" int;;
+let qr_width   = field qrcode "width"   int;;
+let _qr_data   = field qrcode "data"    (ptr char);;
+let () = seal qrcode;;
+
+let encode_string =
+  foreign "QRcode_encodeString"
+    (string @-> int @-> int @-> int @-> int @-> returning (ptr qrcode));;
+
+let qr_free =
+  foreign "QRcode_free"
+    (ptr qrcode @-> returning void);;
+
 let () =
-  let qr = Qrc.encode "unsandbox-qr-ok" in
-  let rows = Array.length (Qrc.to_matrix qr) in
-  Printf.printf "QR:unsandbox-qr-ok:ROWS:%d\n" rows
+  let qr = encode_string "unsandbox-qr-ok" 0 1 2 1 in
+  let w = getf !@qr qr_width in
+  Printf.printf "QR:unsandbox-qr-ok:ROWS:%d\n" w;
+  qr_free qr;;