Require Varnish 4.1 and set version 0.1.

README.rst

@@ -133,3 +133,9 @@ Description
 
 Example
 	std.log("Using VMOD blobsha256 version " + blobsha256.version());
+
+REQUIREMENTS
+------------
+
+This VMOD requires Varnish 4.1. See the project repository for
+versions that are compatible with later versions of Varnish.

configure.ac

 AC_PREREQ(2.59)
 AC_COPYRIGHT([Copyright (c) 2016 UPLEX - Nils Goroll Systemoptimierung])
-AC_INIT([libvmod-blobsha256], [trunk])
+AC_INIT([libvmod-blobsha256], [0.1])
 AC_CONFIG_MACRO_DIR([m4])
 m4_ifndef([VARNISH_VMOD_INCLUDES], AC_MSG_ERROR([Need varnish.m4 -- see README.rst]))
 AC_CONFIG_SRCDIR(src/vmod_blobsha256.vcc)
@@ -59,7 +59,7 @@ AS_VAR_IF([$1], [""], [$5], [$4])dnl
 ])# PKG_CHECK_VAR
 ])
 
-PKG_CHECK_MODULES([libvarnishapi], [varnishapi])
+PKG_CHECK_MODULES([libvarnishapi], [varnishapi < 5.0.0])
 PKG_CHECK_VAR([LIBVARNISHAPI_DATAROOTDIR], [varnishapi], [datarootdir])
 PKG_CHECK_VAR([LIBVARNISHAPI_BINDIR], [varnishapi], [bindir])
 PKG_CHECK_VAR([LIBVARNISHAPI_SBINDIR], [varnishapi], [sbindir])

src/vmod_blobsha256.vcc

@@ -69,3 +69,9 @@ Description
 
 Example
 	std.log("Using VMOD blobsha256 version " + blobsha256.version());
+
+REQUIREMENTS
+------------
+
+This VMOD requires Varnish 4.1. See the project repository for
+versions that are compatible with later versions of Varnish.