sphinx加载索引信息文件

加载sphinx索引信息等文件

searchd.cpp main() ->
searchd.cpp RotateIndexGreedy() ->
searchd.cpp Prealloc(...) ->
sphinx.cpp  CSphIndex::Preread()      ->
sphinx.cpp  CSphIndex_VLN::Preread()  ->
sphinx.cpp  CSphIndex_VLN::PrereadSharedBuffer() ->
sphinxint.h CSphAutofile::CSphAutofile(...) ->
sphinx.cpp  CSphAutofile::Open(...) ->
sphinx.cpp  CSphAutofile::m_iFD (file handle)