The embedded library is still broken, but there the situation
with dependencies is even more broken.


sql/Makefile.am:
  Fix broken automatic dependency tracking of Automake in sql/:
  use a convenience library to specify additional includes that
  are required to compile files ha_ndbcluster_*, and then
  add this convenience library to the main project.
  The embedded library is still broken, but there the situation
  with dependencies is even more broken.