QString: use qsizetype more

It's last legacy int

Pick-to: 6.6 6.5 6.2
Change-Id: I691f7b15dead91166831cdf6c33a9f4d2d58b62e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/text/qstring.cpp

@@ -3673,7 +3673,7 @@ static void replace_with_copy(QString &str, size_t *indices, qsizetype nIndices,
     QString copy{ newSize, Qt::Uninitialized };
     QString::DataPointer &copy_d = copy.data_ptr();
     auto dst = copy_d.begin();
-    for (int i = 0; i < nIndices; ++i) {
+    for (qsizetype i = 0; i < nIndices; ++i) {
         auto hit = str_d.begin() + indices[i];
         dst = std::copy(src_start, hit, dst);
         dst = std::copy_n(after_b, alen, dst);