Fix XCB on endian mismatched client and server with SHM off

If SHM is disabled, that code path already does its own bswaping.

Change-Id: I6c17f6c5c5502c8f89098d38d931b6b8f50b2640
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

src/plugins/platforms/xcb/qxcbconnection.h

@@ -412,6 +412,8 @@ public:
 
     bool imageNeedsEndianSwap() const
     {
+        if (!hasShm())
+            return false; // The non-Shm path does its own swapping
 #if Q_BYTE_ORDER == Q_BIG_ENDIAN
         return m_setup->image_byte_order != XCB_IMAGE_ORDER_MSB_FIRST;
 #else