pgsql: Allow multiple hostaddrs to go with multiple hostnames.

Allow multiple hostaddrs to go with multiple hostnames.

Also fix two other issues, while we're at it:

* In error message on connection failure, if multiple network addresses
were given as the host option, as in "host=127.0.0.1,127.0.0.2", the
error message printed the address twice.

* If there were many more ports than hostnames, the error message would
always claim that there was one port too many, even if there was more than
one. For example, if you gave 2 hostnames and 5 ports, the error message
claimed that you gave 2 hostnames and 3 ports.

Discussion: https://www.postgresql.org/message-id/10badbc6-4d5a-a769-623a-f7ada43e14dd@iki.fi

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7b02ba62e9ffad5b14c24756a0c2aeae839c9d05

Modified Files
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doc/src/sgml/libpq.sgml | 55 +++++++-
src/interfaces/libpq/fe-connect.c | 258 ++++++++++++++++++++++++--------------
src/interfaces/libpq/libpq-int.h | 3 +-
3 files changed, 219 insertions(+), 97 deletions(-)