- Users can now specify particular components from Ceres, such as
  SuiteSparse support) that must be present in a detected version of
  Ceres in order for it to be reported as found by find_package().
- This allows users to specify for example that they require a version
  of Ceres with SuiteSparse support at configure time, rather than
  finding out only at run time that Ceres was not compiled with the
  options they require.
- The list of available components are built directly from the Ceres
  compile options.
- The meta-module SparseLinearAlgebraLibrary is present if at least
  one sparse linear algebra backend is available.

Change-Id: I65f1ddfd7697e6dd25bb4ac7e54f5097d3ca6266