Add libpq include directory to script.

src/tools/pginclude/pgcompinclude

 :
 # report which #include files can not compile on their own
 # takes -v option to display compile failure message and line numbers
-# $PostgreSQL: pgsql/src/tools/pginclude/pgcompinclude,v 1.5 2006/07/10 18:39:32 momjian Exp $
+# $PostgreSQL: pgsql/src/tools/pginclude/pgcompinclude,v 1.6 2006/07/11 02:01:24 momjian Exp $
 
 trap "rm -f /tmp/$$.c /tmp/$$.o /tmp/$$ /tmp/$$a" 0 1 2 3 15
 find . \( -name CVS -a -prune \) -o -name '*.h' -type f -print | while read FILE
@@ -14,7 +14,7 @@ do
 	pgdefine "$FILE" >>/tmp/$$.c
 	echo "}" >>/tmp/$$.c
 	cc $CFLAGS -fsyntax-only -Werror -Wall -Wmissing-prototypes -Wmissing-declarations \
-		-I/pg/include -I/pg/backend -I`dirname $FILE` -c /tmp/$$.c -o /tmp/$$.o >/tmp/$$ 2>&1
+		-I/pg/include -I/pg/backend -I/pg/interfaces/libpq -I`dirname $FILE` -c /tmp/$$.c -o /tmp/$$.o >/tmp/$$ 2>&1
 	if [ "$?" -ne 0 ]
 	then	echo "$FILE"
 		if [ "$1" = "-v" ]