JUMBO Stewart Forster speedup patch:

JUMBO Stewart Forster speedup patch:
    1) aiops.c and aiops.h are a threaded implementation of asynchronous file
       operations.
    2) async_io.c and async_io.h are complete rewrites of the old versions.
    3) I have rewritten all disk file operations of squid to support
       the idea of callbacks except where not required.
    4) UDP_HIT_OBJ not supported.
    5) Background validation of 'tainted' swap log entries.
    6) Modified storeWriteCleanLog to create the log file using the
       open/write rather than fopen/printf.
    7) Added the E_INTR error response to handle badly interrupted
       system calls.