fix compiler warning
fix compiler warning

tsingpan/mochiweb,vinoski/mochiweb,robertkowalski/mochiweb,riak-synrc/mochiweb,vinoski/mochiweb,danogwok/mochiweb,danogwok/mochiweb,ubf/mochiweb,rcouch/couchdb-mochiweb,robertkowalski/mochiweb,tsingpan/mochiweb,ubf/mochiweb,jasonjli/mochiweb,jasonjli/mochiweb