Port QByteDataBuffer to qsizetype

Less impedance mismatch with the other Qt containers.

As a drive-by, fix code style in the touched lines, and remove
superfluous inline keywords.

Pick-to: 6.4 6.3
Change-Id: I2c9444a8f956e58c361104a19f55fcc783cd1a1d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/text/qbytedata_p.h

@@ -229,7 +229,7 @@ public:
     }
 
     // the number of QByteArrays
-    inline int bufferCount() const
+    qsizetype bufferCount() const
     {
         return buffers.length();
     }
@@ -247,7 +247,7 @@ public:
             return buffers.first().size() - firstPos;
     }
 
-    inline QByteArray& operator[](int i)
+    QByteArray &operator[](qsizetype i)
     {
         if (i == 0)
             squeezeFirst();
@@ -256,7 +256,7 @@ public:
     }
 
     inline bool canReadLine() const {
-        int i = 0;
+        qsizetype i = 0;
         if (i < buffers.length()) {
             if (buffers.at(i).indexOf('\n', firstPos) != -1)
                 return true;

src/network/access/qnetworkreplyimpl.cpp

@@ -458,7 +458,7 @@ void QNetworkReplyImplPrivate::appendDownstreamData(QByteDataBuffer &data)
     }
 
     qint64 bytesWritten = 0;
-    for (int i = 0; i < data.bufferCount(); i++) {
+    for (qsizetype i = 0; i < data.bufferCount(); ++i) {
         QByteArray const &item = data[i];
 
         if (cacheSaveDevice)