added our own nqp::unlink() op

Which might be able to delete write-protected files on windows.

src/vm/parrot/QAST/Operations.nqp

@@ -1689,17 +1689,7 @@ QAST::Operations.add_core_op('chmod', -> $qastcomp, $op {
         $op[0],
         $op[1]) );
 });
-QAST::Operations.add_core_op('unlink', -> $qastcomp, $op {
-    if +$op.list != 1 {
-        nqp::die("The 'unlink' op expects one operand");
-    }
-    $qastcomp.as_post(QAST::Op.new(
-        :op('callmethod'),
-        :name('unlink'),
-        QAST::VM.new( :pirop('new__Ps'),
-                      QAST::SVal.new( :value('OS') ) ),
-        $op[0] ) );
-});
+QAST::Operations.add_core_pirop_mapping('unlink', 'nqp_delete_f', 'Is');
 QAST::Operations.add_core_op('rmdir', -> $qastcomp, $op {
     if +$op.list != 1 {
         nqp::die("The 'rmdir' op expects one operand");

src/vm/parrot/ops/nqp.ops

@@ -3514,6 +3514,32 @@ inline op nqp_getlexrelcaller(out PMC, in PMC, in STR) :base_core {
     $1 = result;
 }
 
+inline op nqp_delete_f(out INT, in STR) :base_core {
+#ifdef WIN32
+    char* const filename = Parrot_str_to_platform_cstring(interp, $2);
+    DWORD attrs          = GetFileAttributesA(filename);
+    INTVAL ret;
+
+    if (attrs == 0xFFFFFFFF) {
+        errno = ENOENT;
+        ret = -1;
+    }
+    else if (attrs & FILE_ATTRIBUTE_READONLY) {
+        (void)SetFileAttributesA(filename, attrs & ~FILE_ATTRIBUTE_READONLY);
+        $1 = unlink(filename);
+        if (ret == -1)
+            (void)SetFileAttributesA(filename, attrs);
+    }
+    else
+        ret = unlink(filename);
+
+    $1 = ret;
+#else
+    char* const filename = Parrot_str_to_platform_cstring(interp, $2);
+    $1 = unlink(filename);
+#endif
+}
+
 inline op nqp_shell(out INT, in STR, in STR, in PMC) {
      STRING *command = $2;  
      STRING *dir = $3;