Avoid access past end of vector
Avoid access past end of vector

In most configurations this access would be optimized out (as it is
never used) but this is not always the case.

Fixes #1002

libgeos/libgeos,mwtoews/libgeos,mwtoews/libgeos,libgeos/libgeos,libgeos/libgeos,mwtoews/libgeos,mwtoews/libgeos,libgeos/libgeos,mwtoews/libgeos,libgeos/libgeos,mwtoews/libgeos,mwtoews/libgeos