--with-pgsql-libs is ignored

If I specify to configure script --with-pgsql-libs, it is ignored.
following code is useful?

=== modified file 'm4/ac_check_pgsql.m4'
--- m4/ac_check_pgsql.m4 2015-01-29 05:53:15 +0000
+++ m4/ac_check_pgsql.m4 2015-01-29 06:00:34 +0000
@@ -28,6 +28,12 @@
                 [ac_cv_pgsql_libs=$withval])
 fi

+if test [ -n "$ac_cv_pgsql_libs" ]
+then
+ AC_CACHE_CHECK([PostgreSQL libraries], [ac_cv_pgsql_libs], [ac_cv_pgsql_libs=""])
+ PGSQL_LIBS="-L$ac_cv_pgsql_libs -lpq"
+fi
+
 # If some path is missing, try to autodetermine with pgsql_config
 if test [ -z "$ac_cv_pgsql_includes" -o -z "$ac_cv_pgsql_libs" ]
 then