pgsql: Fix crash caused by NULL lookup when reporting IP address of fai

Fix crash caused by NULL lookup when reporting IP address of failed
libpq connection, per report from Magnus.  This happens only on GIT
master and only on Win32 because that is the platform where "" maps to
an IP address (localhost).

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=postgresql.git;a=commitdiff;h=48da2b87e3f292534a26d3bacc2a13f7b62a34c8

Modified Files
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src/interfaces/libpq/fe-connect.c |    3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)