configure: move storage dir check to its own file

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>

m4/virt-storage-dir.m4

@@ -0,0 +1,33 @@
+dnl The storage dir check
+dnl
+dnl Copyright (C) 2016 Red Hat, Inc.
+dnl
+dnl This library is free software; you can redistribute it and/or
+dnl modify it under the terms of the GNU Lesser General Public
+dnl License as published by the Free Software Foundation; either
+dnl version 2.1 of the License, or (at your option) any later version.
+dnl
+dnl This library is distributed in the hope that it will be useful,
+dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+dnl Lesser General Public License for more details.
+dnl
+dnl You should have received a copy of the GNU Lesser General Public
+dnl License along with this library.  If not, see
+dnl <http://www.gnu.org/licenses/>.
+dnl
+
+AC_DEFUN([LIBVIRT_STORAGE_ARG_DIR], [
+  LIBVIRT_ARG_WITH([STORAGE_DIR], [directory backend for the storage driver], [yes])
+])
+
+AC_DEFUN([LIBVIRT_STORAGE_CHECK_DIR], [
+  if test "$with_storage_dir" = "yes" ; then
+    AC_DEFINE_UNQUOTED([WITH_STORAGE_DIR], 1, [whether directory backend for storage driver is enabled])
+  fi
+  AM_CONDITIONAL([WITH_STORAGE_DIR], [test "$with_storage_dir" = "yes"])
+])
+
+AC_DEFUN([LIBVIRT_STORAGE_RESULT_DIR], [
+  LIBVIRT_RESULT([Dir], [$with_storage_dir])
+])