Fix Wsign-compare warning/error

[roystgnr]

#3208 is failing a few of the devel->master CI checks because of this.

https://civet.inl.gov/event/94816/

[roystgnr]

Added the failing CI recipes here.

[jwpeterson]

Ugh. I don't get how it passed all the CI though, don't we have some -Werror recipes on devel still?

[roystgnr]

We do, but I'm betting we only have them with 64-bit PETSc right now, and -Wsign-compare thinks that int64 > uint32 is a fine thing to test.

[roystgnr]

And hopefully that fixes the LIBMESH_CHKERR+exceptions-disabled+non-ParallelObject-callback-function interaction too. I'd appreciate another set of eyes on the refactoring getting rid of _max_its, though.

[jwpeterson]

../src/solvers/petsc_nonlinear_solver.C: In function 'PetscErrorCode libMesh::libmesh_petsc_recalculate_monitor(SNES, PetscInt, PetscReal, void*)':
../src/solvers/petsc_nonlinear_solver.C:117:52: error: 'ctx' was not declared in this scope; did you mean 'mctx'?
  117 |       static_cast<PetscNonlinearSolver<Number> *> (ctx);
      |                                                    ^~~
      |                                                    mctx
../src/solvers/petsc_nonlinear_solver.C: In constructor 'libMesh::PetscNonlinearSolver<T>::PetscNonlinearSolver(libMesh::PetscNonlinearSolver<T>::sys_type&)':
../src/solvers/petsc_nonlinear_solver.C:650:3: error: class 'libMesh::PetscNonlinearSolver<T>' does not have any field named '_max_its'
  650 |   _max_its(0)
      |   ^~~~~~~~
../src/solvers/petsc_nonlinear_solver.C: In member function 'virtual std::pair<unsigned int, double> libMesh::PetscNonlinearSolver<T>::solve(libMesh::SparseMatrix<T>&, libMesh::NumericVector<T>&, libMesh::NumericVector<T>&, double, unsigned int)':
../src/solvers/petsc_nonlinear_solver.C:883:7: error: '_max_its' was not declared in this scope
  883 |       _max_its = reuse_preconditioner_max_its();
      |       ^~~~~~~~

[moosebuild]

Job Coverage on a9a8f02 wanted to post the following:

Coverage

	b6c94e	#3349 a9a8f0
	Total	Total	+/-	New
Rate	55.72%	55.72%	+0.00%	44.44%
Hits	44954	44954	-	4
Misses	35722	35720	-2	5

Diff coverage report

Full coverage report

Warnings

• New new line coverage rate 44.44% is less than the suggested 90.0%

This comment will be updated on new commits.