Fix uninitialized variable bug in libHilbert.
Fix uninitialized variable bug in libHilbert.

This was causing undefined behavior on Linux in my simple libHilbert
inverse mapping tests, but seemed to work fine on OSX.  Not sure if it
would affect other libmesh code...

Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh