Allow spaces in connection strings in SSL tests

Connection strings can have items with spaces in them, wrapped in
quotes.  The tests however ran a SELECT '$connstr' upon connection which
broke on the embedded quotes.  Use dollar quotes on the connstr to
protect against this.  This was hit during the development of the macOS
Secure Transport patch, but is independent of it.

Author: Daniel Gustafsson <daniel@yesql.se>

src/test/ssl/ServerSetup.pm

@@ -42,7 +42,7 @@ sub run_test_psql
 	my $logstring = $_[1];
 
 	my $cmd = [
-		'psql', '-X', '-A', '-t', '-c', "SELECT 'connected with $connstr'",
+		'psql', '-X', '-A', '-t', '-c', "SELECT \$\$connected with $connstr\$\$",
 		'-d', "$connstr" ];
 
 	my $result = run_log($cmd);