You don't need to change HOST_CONFIGURE_ARGS I suppose.
diff --git a/libs/postgresql/Makefile b/libs/postgresql/Makefile
index f3b677073..5203ee434 100644
--- a/libs/postgresql/Makefile
+++ b/libs/postgresql/Makefile
@@ -31,7 +31,7 @@ include $(INCLUDE_DIR)/package.mk
define Package/libpq
SECTION:=libs
CATEGORY:=Libraries
- DEPENDS:=+libpthread
+ DEPENDS:=+libopenssl +libpthread
TITLE:=PostgreSQL client library
URL:=http://www.postgresql.org/
SUBMENU:=Database
@@ -146,7 +146,7 @@ CONFIGURE_ARGS += \
--without-bonjour \
--without-gssapi \
--without-ldap \
- --without-openssl \
+ --with-openssl \
--without-pam \
--without-perl \
--without-python \
Good luck!