MINOR: hlua: Use flags of HTX blocks to detect EOM from an HTTP applet

MINOR: hlua: Use flags of HTX blocks to detect EOM from an HTTP applet

When we try to get request's data from an HTTP applet, instead of testing
HTX_FL_HAS_EOM flag on the message, we now rely on the flags of HTX blocks.
The logic remains the same, when all DATA blocks were consumed, we consider
the request as fully received. It may be when the blocks with the EOM flag
was removed or because a trailer was seen.