Fix up configure so it finds mkinstalldirs

As an object lesson in why autoreconf is fundamentally unsafe, the
newer version of nls.m4 no longer handles @MKINSTALLDIRS@.  So add
this back, since our Makefiles depend on it.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/acinclude.m4 b/acinclude.m4
index cf84acc..4c8a77c 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -128,3 +128,21 @@
         AC_SUBST(ifGNUmake)
         AC_SUBST(ifNotGNUmake)
 ] )
+# was originally from nls.m4 serial 1 (gettext-0.12)
+AC_DEFUN([AM_MKINSTALLDIRS],
+[
+  dnl If the AC_CONFIG_AUX_DIR macro for autoconf is used we possibly
+  dnl find the mkinstalldirs script in another subdir but $(top_srcdir).
+  dnl Try to locate it.
+  MKINSTALLDIRS=
+  if test -n "$ac_aux_dir"; then
+    case "$ac_aux_dir" in
+      /*) MKINSTALLDIRS="$ac_aux_dir/mkinstalldirs" ;;
+      *) MKINSTALLDIRS="\$(top_builddir)/$ac_aux_dir/mkinstalldirs" ;;
+    esac
+  fi
+  if test -z "$MKINSTALLDIRS"; then
+    MKINSTALLDIRS="\$(top_srcdir)/mkinstalldirs"
+  fi
+  AC_SUBST(MKINSTALLDIRS)
+])