Fix location for configured header.

target_include_header includes the BINARY_DIR not BINARY_DIR/src

@ben.boeckel @shawn.waldon Please review.

+1

@ben.boeckel Thanks Ben. Can you merge this? I don't think I have rights to do this.

merged

mentioned in commit 1f3d41ae

Please use the for/vtk-20180925-g1f3d41a tag when updating pugixml in VTK.

Is that to see what SHA we used for the code in VTK?

No, it's so that it's easier to tell what tag to base off of for changes on the release branch (assuming that the main for/vtk has moved on and isn't compatible anymore).