QString: in remove() use d->erase() for all code paths

Use the minimum of "len" and "size() - pos", logically we'll only ever
remove characters up-to the end of the array.

This eliminates one if branch, and d->erase() can handle all the use-cases.

After making this change I looked at QByteArray::remove() and it has
similar logic, so it should be correct™.

Change-Id: Ife6c552f8a3f3dda1d5a1da12b80a60790f3bae4
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/text/qstring.cpp

@@ -3279,11 +3279,11 @@ QString &QString::remove(qsizetype pos, qsizetype len)
 {
     if (pos < 0)  // count from end of string
         pos += size();
+
     if (size_t(pos) >= size_t(size())) {
         // range problems
-    } else if (len >= size() - pos) {
-        resize(pos); // truncate
     } else if (len > 0) {
+        len = std::min(len, size() - pos);
         detach();
         d->erase(d.begin() + pos, len);
         d.data()[d.size] = u'\0';