Trivial change to save intel-12.0 from itself.

Seriously, this fixes a new issue:

  CXX    src/fe/libmesh_opt_la-fe_hierarchic.lo
src/error_estimation/kelly_error_estimator.C(140) (col. 45): internal error: 0_1451

compilation aborted for src/error_estimation/kelly_error_estimator.C (code 4)
make[1]: *** [src/error_estimation/libmesh_opt_la-kelly_error_estimator.lo] Error 1
make[1]: *** Waiting for unfinished jobs....

which must have been triggered by changes in the underlying header files,
as this file has not changed in ages.