Fix thread safety issue in chunked http transfers.

* The use of a static variable for storing the chunk size made it shared between all instances of BUrlProtoclHttp.
* Inline the function at the single place where it is used, and allocate the variable on the stack instead.

The whole receiving loop should be split into chunked and non-chunked variants to improve code readability.

headers/os/net/UrlProtocolHttp.h

@@ -54,9 +54,6 @@ private:
 			void				_ParseStatus();
 			void				_ParseHeaders();
 
-			void				_CopyChunkInBuffer(char** buffer,
-									ssize_t* bytesReceived);
-
 			void				_AddOutputBufferLine(const char* line);