pgsql: Move canAcceptConnections check from ProcessStartupPacket to cal

Move canAcceptConnections check from ProcessStartupPacket to caller.

The check is not about processing the startup packet, so the calling
function seems like a more natural place. I'm also working on a patch
that moves 'canAcceptConnections' out of the Port struct, and this
makes that refactoring more convenient.

Reviewed-by: Tristan Partin
Discussion: https://www.postgresql.org/message-id/7a59b073-5b5b-151e-7ed3-8b01ff7ce9ef@iki.fi

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/16671ba6e717ea307a3f61e8ab4f866cd6834772

Modified Files
--------------
src/backend/postmaster/postmaster.c | 86 ++++++++++++++++++-------------------
1 file changed, 43 insertions(+), 43 deletions(-)