This makes the target location consistent with other auto-generated
files like config_formats.h, config_core.h, and config_functions.h and
simplifies the build of clickhouse_common.
* Refactoring: part 1
* Refactoring: part 2
* Handle request using ReadBuffer interface
* Struggles with ReadBuffer's
* Fix URI parsing
* Implement parsing of multipart/form-data
* Check HTTP_LENGTH_REQUIRED before eof() or will hang
* Fix HTTPChunkedReadBuffer
* Fix build and style
* Fix test
* Resist double-eof
* Fix arcadian build