Remove unused stream methods

They were accidentally left unused in fbad8a9 so they haven't been used
in some time.

common/rdr/FdInStream.h

@@ -47,7 +47,6 @@ namespace rdr {
     void setBlockCallback(FdInStreamBlockCallback* blockCallback);
     int getFd() { return fd; }
     size_t pos();
-    void readBytes(void* data, size_t length);
 
     void startTiming();
     void stopTiming();