use std::size_t and std::ptrdiff_t in C++ code (bug #60471) Files affected: make_int.cc, file-editor-tab.cc, octave-qscintilla.cc, Cell.cc, Cell.h, call-stack.cc, call-stack.h, cellfun.cc, data.cc, debug.cc, dlmread.cc, error.cc, event-queue.h, fcn-info.cc, fcn-info.h, file-io.cc, ft-text-renderer.cc, gl2ps-print.cc, graphics.cc, graphics.in.h, help.cc, hex2num.cc, input.cc, latex-text-renderer.cc, load-path.cc, load-save.cc, load-save.h, ls-hdf5.cc, ls-mat-ascii.cc, ls-mat5.cc, ls-oct-text.cc, mex.cc, mexproto.h, mxarray.h, oct-map.cc, oct-stream.cc, oct-stream.h, pager.cc, pager.h, pr-output.cc, regexp.cc, settings.h, stack-frame.cc, stack-frame.h, strfns.cc, syminfo.cc, symrec.h, symscope.cc, symscope.h, symtab.cc, sysdep.cc, toplev.cc, utils.cc, utils.h, variables.cc, __fltk_uigetfile__.cc, __init_fltk__.cc, audioread.cc, gzip.cc, cdef-class.cc, cdef-manager.cc, cdef-method.cc, cdef-object.cc, cdef-object.h, ov-base-diag.cc, ov-base-diag.h, ov-base-mat.cc, ov-base-mat.h, ov-base-scalar.cc, ov-base-scalar.h, ov-base-sparse.h, ov-base.cc, ov-base.h, ov-cell.cc, ov-cell.h, ov-ch-mat.cc, ov-class.cc, ov-class.h, ov-classdef.cc, ov-fcn-handle.cc, ov-java.cc, ov-lazy-idx.h, ov-perm.cc, ov-perm.h, ov-range.h, ov-str-mat.cc, ov-struct.cc, ov-struct.h, ov-usr-fcn.cc, ov-usr-fcn.h, ov.cc, ov.h, ovl.cc, octave.cc, bp-table.cc, jit-ir.cc, jit-ir.h, jit-typeinfo.cc, jit-typeinfo.h, jit-util.h, lex.h, lex.ll, oct-lvalue.cc, oct-parse.yy, parse.h, profiler.h, pt-eval.cc, pt-eval.h, pt-jit.cc, pt-jit.h, pt-pr-code.cc, pt-tm-const.cc, pt-tm-const.h, Array.h, CMatrix.cc, DiagArray2.h, PermMatrix.h, Sparse.h, dMatrix.cc, fCMatrix.cc, fMatrix.cc, bsxfun-defs.cc, oct-fftw.cc, oct-fftw.h, randpoisson.cc, sparse-chol.cc, mx-inlines.cc, file-ops.cc, lo-sysdep.cc, oct-env.cc, oct-time.cc, action-container.cc, action-container.h, base-list.h, caseless-str.h, cmd-edit.cc, cmd-hist.cc, data-conv.cc, data-conv.h, f77-fcn.h, file-info.cc, file-info.h, kpse.cc, kpse.h, lo-cutils.h, lo-hash.h, lo-regexp.cc, oct-base64.cc, oct-base64.h, oct-binmap.h, oct-glob.cc, oct-shlib.cc, oct-shlib.h, oct-sort.cc, oct-sparse.h, oct-string.cc, quit.cc, unwind-prot.h, url-transfer.cc, main.in.cc, mkoctfile.in.cc, and shared-fcns.h. (grafted from aef11bb4e6d1f303ad9de5688fcb7244ef48867e)

--- a/libinterp/corefcn/input.cc	Wed Apr 28 22:23:39 2021 -0400
+++ b/libinterp/corefcn/input.cc	Wed Apr 28 22:57:42 2021 -0400
@@ -158,7 +158,7 @@
   {
     string_vector names;
 
-    size_t pos = text.rfind ('.');
+    std::size_t pos = text.rfind ('.');
     bool array = false;
 
     if (pos != std::string::npos)
@@ -267,13 +267,13 @@
   is_completing_dirfns (void)
   {
     static std::string dirfns_commands[] = {"cd", "isfile", "isfolder", "ls"};
-    static const size_t dirfns_commands_length = 4;
+    static const std::size_t dirfns_commands_length = 4;
 
     bool retval = false;
 
     std::string line = command_editor::get_line_buffer ();
 
-    for (size_t i = 0; i < dirfns_commands_length; i++)
+    for (std::size_t i = 0; i < dirfns_commands_length; i++)
       {
         int index = line.find (dirfns_commands[i] + ' ');
 
@@ -295,7 +295,7 @@
     static std::string prefix;
     static std::string hint;
 
-    static size_t hint_len = 0;
+    static std::size_t hint_len = 0;
 
     static int list_index = 0;
     static int name_list_len = 0;
@@ -629,7 +629,7 @@
     if (input_buf.empty ())
       error ("input: reading user-input failed!");
 
-    size_t len = input_buf.length ();
+    std::size_t len = input_buf.length ();
 
     octave_diary << input_buf;
 
@@ -891,7 +891,7 @@
       {
         std::string input = octave_gets (prompt, m_eof);
 
-        size_t len = input.size ();
+        std::size_t len = input.size ();
 
         if (len == 0)
           {
@@ -910,10 +910,10 @@
               }
           }
 
-        size_t beg = 0;
+        std::size_t beg = 0;
         while (beg < len)
           {
-            size_t end = input.find ('\n', beg);
+            std::size_t end = input.find ('\n', beg);
 
             if (end == std::string::npos)
               {
@@ -979,9 +979,9 @@
       {
         // convert encoding to UTF-8 before returning string
         const char *src = src_str.c_str ();
-        size_t srclen = src_str.length ();
+        std::size_t srclen = src_str.length ();
 
-        size_t length;
+        std::size_t length;
         uint8_t *utf8_str;
 
         utf8_str = octave_u8_conv_from_encoding (encoding.c_str (), src, srclen,