typedef conflict between geos and opencv2 when building on Xenial

[evenator]

When building on Ubuntu 16.04, the swri_geometry_util fails due to the following error:

In file included from /usr/include/geos/geom/CoordinateSequence.h:19:0,
                from /usr/include/geos/geom/CoordinateArraySequence.h:21,
                 from /root/ros/ws_ci_src/src/ci_src/swri_geometry_util/src/intersection.cpp:34:
/usr/include/geos/platform.h:66:26: error: conflicting declaration 'typedef long long int int64'
    typedef long long int int64;                      
                          ^
In file included from /usr/include/opencv2/core/core.hpp:49:0,
                from /root/ros/ws_ci_src/src/ci_src/swri_geometry_util/include/swri_geometry_util/intersection.h:31,
               from /root/ros/ws_ci_src/src/ci_src/swri_geometry_util/src/intersection.cpp:32:
/usr/include/opencv2/core/types_c.h:163:20: note: previous declaration as 'typedef int64_t int64'
    typedef int64_t int64;                            
                    ^