/*
   * Create solvable with +name+ and +evr+ in the Repo
   * Can optionally be passed an architecture, defaulting to +noarch+
   *
   * call-seq:
   *   repo.create_solvable("test", "42.0-1")
   *   repo.create_solvable("foo", "1.2-3", "x86_64")
   *
   */
  XSolvable *create_solvable( const char *name, const char *evr, const char *arch = NULL )