maint: Tweaks to remove compiler warnings. * libgui/src/find-files-model.cc(rowCount, columnCount): Eliminate unused input parameter p. * libinterp/corefcn/octave-link.cc(F__octave_link_file_dialog__): Use signed int in for loop index for comparison to octave_idx_type. * libinterp/corefcn/txt-eng-ft.cc(ft_render::visit): Initialize all of mbstate_t structure (not just first field) with memset() to 0. * libinterp/parse-tree/oct-parse.in.yy(F__parse_file__): Remove unused nargout parameter.

--- a/libinterp/corefcn/octave-link.cc
+++ b/libinterp/corefcn/octave-link.cc
@@ -255,7 +255,7 @@
 
               std::list<std::string>::iterator it = items_lst.begin ();
 
-              for (unsigned int idx = 0; idx < nel; idx++)
+              for (int idx = 0; idx < nel; idx++)
                 {
                   items.xelem (idx) = *it;
                   it++;