QByteArray: delegate to replace(char,char) from replace(QBAV,QBAV)

Don't go and build (among other things) a Boyer-Moore table for the
trivially optimizable replacement of single characters with single
characters. Just call the existing replace(char, char) overload.

Pick-to: 6.9 6.8
Change-Id: Ic69527bdaa5ce95bf937295366b94366e2ace933
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Ahmad Samir <a.samirh78@gmail.com>

src/corelib/text/qbytearray.cpp

@@ -2533,6 +2533,9 @@ QByteArray &QByteArray::replace(QByteArrayView before, QByteArrayView after)
     const char *a = after.data();
     qsizetype asize = after.size();
 
+    if (bsize == 1 && asize == 1)
+        return replace(*b, *a); // use the fast char-char algorithm
+
     if (isNull() || (b == a && bsize == asize))
         return *this;