Merge pull request #2669 in SNORT/snort3 from ~DAVMCPHE/snort3:max_pdu_only to master

Merge pull request #2669 in SNORT/snort3 from ~DAVMCPHE/snort3:max_pdu_only to master

Squashed commit of the following:

commit c3b1baf2fd09a5aaf58ee09a26efd7048c8d3ea9
Author: davis mcpherson <davmcphe@cisco.com>
Date:   Tue Dec 22 11:30:01 2020 -0500

    stream_tcp: delete redundant calls to check if the tcp packet contains a data payload

commit ed0484fe30ec0e9fbd7808aaab06dbdbc8d61a75
Author: davis mcpherson <davmcphe@cisco.com>
Date:   Tue Dec 22 11:28:56 2020 -0500

     stream_tcp: on midstream pickup, when first packet is a data segment, set flag on talker tracker to reinit seglist base seg on first received data packet

commit c2d0eadde2b5eee60372c891b931bc39f626fc4f
Author: davis mcpherson <davmcphe@cisco.com>
Date:   Tue Dec 1 16:51:47 2020 -0500

    stream_tcp: fix issues causing overrun of the pdu reassembly buffer.  make splitters authoritative of size of the reassembled pdu

    rpc_decode: implement adjust_to_fit for RPC splitter