Fixed confusing indentation, no behaviour change

Hopefully it's the indentation that was wrong,
and not that braces were missing... this seems
to be the consensus on vtk-dev.

Warned by clang's experimental -Windent
"warning: statement has higher indent than preceding if, but is not part of it"

Change-Id: I921d4849f1da362e7301ed0cacb2520b3508fd01
Merge topic 'vtkCirclePackFrontChainLayoutStrategy-indent' into master

3d1f2d74 Fixed confusing indentation, no behaviour change