cyrus-sasl: Fix plugin location.

component/cyrus-sasl/buildout.cfg

@@ -8,7 +8,7 @@ extends =
 recipe = slapos.recipe.cmmi
 url = ftp://ftp.cyrusimap.org/cyrus-sasl/cyrus-sasl-2.1.26.tar.gz
 md5sum = a7f4e5e559a0e37b3ffc438c9456e425
-
+location = ${buildout:parts-directory}/${:_buildout_section_name_}
 configure-options =
   --disable-digest
   --disable-gssapi
@@ -18,6 +18,7 @@ configure-options =
   --without-openssl
   --without-pam
   --without-saslauthd
+  --with-plugindir=${:location}/lib/sasl2
 # it seems that parallel build sometimes fails.
 make-options =
   -j1