Add connection service file.

src/backend/libpq/pg_service.conf.sample

+#
+#	Connection configuration file
+#
+# A service is a set of named connection parameters.  You may specify
+# multiple services in this file.  Each starts with a service name in  
+# brackets.  Subsequent lines have connection configuration parameters of
+# the pattern  "param=value".  A sample configuration for template1 is 
+# included in this file.  If no database name is specified, it is assumed 
+# to match the service name.  Lines beginning with '#' are comments.
+#
+# Copy this to your sysconf directory (typically /usr/local/pgsql/etc) and
+# rename it pg_service.conf.
+#
+#
+#[template1]
+#user=postgres