pgsql: Instead of a bare recv() to read the server's response to an SSL

Log Message:
-----------
Instead of a bare recv() to read the server's response to an SSL
request packet, use pqReadData(). This has the same effect since
conn->ssl isn't set yet and we aren't expecting more than one byte.
The advantage is that we will correctly detect loss-of-connection
instead of going into an infinite loop. Per report from Hannu Krosing.

Modified Files:
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pgsql/src/interfaces/libpq:
fe-connect.c (r1.297 -> r1.298)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/fe-connect.c.diff?r1=1.297&r2=1.298)