restore disable-nagle logic for connected sockets

Note: Prior to the MPM-as-DSO churn, the following MPMs did not enable this logic:

  WinNT       APR supports no-oping the setsockopt() based on inheriting Nagle from the 
              listening socket on this platform, so the new APR call will be a no-op.
  simple      same as WinNT for at least some Unix-y platforms
  BeOS        shrug



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@758696 13f79535-47bb-0310-9956-ffa450edef68