QHttpNetworkReplyPrivate: Remove unused variable

Oh, and re-remove the spdy protocol handler.

Change-Id: I9ca3517b14ac202eac19ae75d481cfd78d431abb
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

src/network/access/qhttpnetworkreply.cpp

@@ -990,7 +990,6 @@ bool QHttpNetworkReplyPrivate::expectContent()
 
 void QHttpNetworkReplyPrivate::eraseData()
 {
-    compressedData.clear();
     responseData.clear();
 }
 

src/network/access/qhttpnetworkreply_p.h

@@ -262,7 +262,6 @@ public:
     bool autoDecompress;
 
     QByteDataBuffer responseData; // uncompressed body
-    QByteArray compressedData; // compressed body (temporary)
     bool requestIsPrepared;
 
     bool pipeliningUsed;