squid: fix parallel builds

Signed-off-by: Luka Perkov <luka@openwrt.org>

net/squid/Makefile

 
 PKG_NAME:=squid
 PKG_VERSION:=3.5.2
-PKG_RELEASE:=2
+PKG_RELEASE:=3
 
 PKG_LICENSE:=GPL-2.0
 PKG_MAINTAINER:=Luka Perkov <luka@openwrt.org>
 	ac_cv_epoll_works=yes \
 
 define Build/Compile
-	$(MAKE) -C $(PKG_BUILD_DIR)/lib \
-		all
-	$(MAKE) -C $(PKG_BUILD_DIR) \
+	+$(MAKE) $(PKG_JOBS) -C $(PKG_BUILD_DIR)/lib all
+	+$(MAKE) $(PKG_JOBS) -C $(PKG_BUILD_DIR) \
 		DESTDIR="$(PKG_INSTALL_DIR)" \
 		install
 endef