build: Add a wrapper to 'guix environment'.

* build-aux/guix-env: New file.
* configure.ac: Require it.

build-aux/guix-env

@@ -0,0 +1,9 @@
+#!/bin/sh
+# Build an environment that includes all the regular and development
+# dependencies of Cuirass.
+
+set -e -x
+guix environment --ad-hoc \
+  autoconf automake bash coreutils findutils gawk git grep \
+  guile guile-json guile-sqlite3 guix gzip less libgcrypt make \
+  perl pkg-config sed sqlite tar "$@"

configure.ac

@@ -2,6 +2,7 @@ AC_PREREQ([2.61])
 AC_INIT([Cuirass], [0.0.1], [bug-guix@gnu.org])
 AC_CONFIG_SRCDIR([bin/cuirass.in])
 AC_CONFIG_AUX_DIR([build-aux])
+AC_REQUIRE_AUX_FILE([guix-env])
 AC_REQUIRE_AUX_FILE([test-driver.scm])
 AM_INIT_AUTOMAKE([foreign subdir-objects -Wall])
 AM_SILENT_RULES([yes])		# enables silent rules by default