RT 131898: Fix native closures failing on the second run

On the first call of a native sub we create a new subroutine body and replace
the original (stored in the routine's $!do attribute). We also set the
invocation spec so the body will be called instead of the CALL-ME method. This
invocation spec is shared between an original routine and it's clones. If the
routine is a clousre, the body won't be shared as only a clone of the routine
will be actually visible in the lexical scope. So until someone comes up with
a better idea, we won't create an optimized version for a closure anymore.

lib/NativeCall.pm6

@@ -298,6 +298,7 @@ my role Native[Routine $r, $libname where Str|Callable|List|IO::Path|Distributio
     has $!cpp-name-mangler;
     has Pointer $!entry-point;
     has int $!arity;
+    has $!is-clone;
 
     method !setup() {
         $setup-lock.protect: {
@@ -403,9 +404,17 @@ my role Native[Routine $r, $libname where Str|Callable|List|IO::Path|Distributio
         }
     }
 
+    method clone() {
+        my $clone := callsame;
+        nqp::bindattr($clone, $?CLASS, '$!is-clone', 1);
+        $clone
+    }
+
     method CALL-ME(|args) {
         self!setup();
-        self!create-optimized-call() unless $*W; # Avoid issues with compiling specialized version during BEGIN time
+        self!create-optimized-call() unless
+            $!is-clone # Clones and original would share the invokespec but not the $!do attribute
+            or $*W;    # Avoid issues with compiling specialized version during BEGIN time
 
         my Mu $args := nqp::getattr(nqp::decont(args), Capture, '@!list');
         if nqp::elems($args) != $!arity {

t/04-nativecall/01-argless.t

@@ -5,7 +5,7 @@ use CompileTestLib;
 use NativeCall;
 use Test;
 
-plan 3;
+plan 5;
 
 compile_test_lib('01-argless');
 
@@ -20,3 +20,11 @@ pass 'survived the call';
 is Argless(), 2, 'called argless function';
 
 is short(), 3, 'called long_and_complicated_name';
+
+sub test-native-closure() {
+    my sub Argless() is native('./01-argless') returns int32 { * }
+    is Argless(), 2, 'called argless closure';
+}
+
+test-native-closure();
+test-native-closure(); # again cause we may have created an optimized version to run