postgresql: InstallDev pkg-config files for libpq

Signed-off-by: Michael Braun <michael-dev@fami-braun.de>

libs/postgresql/Makefile

@@ -222,6 +222,8 @@ define Build/InstallDev
 	$(CP) $(PKG_INSTALL_DIR)/usr/include/postgresql $(1)/usr/include/
 	$(INSTALL_DIR) $(1)/usr/lib
 	$(CP) $(PKG_INSTALL_DIR)/usr/lib/libpq.{a,so*} $(1)/usr/lib/
+	$(INSTALL_DIR) $(1)/usr/lib/pkgconfig
+	$(CP) $(PKG_INSTALL_DIR)/usr/lib/pkgconfig/libpq.pc $(1)/usr/lib/pkgconfig/
 endef
 
 $(eval $(call HostBuild))