Use zipflow

.gitmodules

+[submodule "foreign/zipflow"]
+	path = foreign/zipflow
+	url = https://github.com/madler/zipflow.git

configure.ac

@@ -4,13 +4,17 @@ AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_HEADERS([config.h])
 
-AM_INIT_AUTOMAKE([1.12 -Wall -Werror foreign parallel-tests])
+AM_INIT_AUTOMAKE([1.12 -Wall -Werror foreign parallel-tests subdir-objects])
 AM_SILENT_RULES([yes])
 AM_PROG_AR
 
 LT_PREREQ([2.2.6])
 LT_INIT([dlopen disable-static])
 
+PKG_CHECK_MODULES([ZLIB], [zlib])
+AC_SUBST(ZLIB_CFLAGS)
+AC_SUBST(ZLIB_LIBS)
+
 AC_ARG_WITH([rst2man],
 	AS_HELP_STRING(
 		[--with-rst2man=PATH],

zipflow @ 913ef458

+Subproject commit 913ef458c51504d1f461f6d3a24d4a1a9bdc2bcc

src/Makefile.am

-AM_CFLAGS = $(VARNISHAPI_CFLAGS)
+AM_CFLAGS = $(VARNISHAPI_CFLAGS) $(ZLIB_CFLAGS) -I../foreign/zipflow
 
 # Modules
 
 vmod_LTLIBRARIES = \
 	libvmod_zipflow.la
 
-libvmod_zipflow_la_LDFLAGS = $(VMOD_LDFLAGS)
-libvmod_zipflow_la_SOURCES = vmod_zipflow.c
+libvmod_zipflow_la_LDFLAGS = $(VMOD_LDFLAGS) $(ZLIB_LIBS)
+libvmod_zipflow_la_SOURCES = \
+	vmod_zipflow.c
 nodist_libvmod_zipflow_la_SOURCES = \
+	../foreign/zipflow/zipflow.c \
 	vcc_zipflow_if.c \
 	vcc_zipflow_if.h