Define ComponentCoordinateExtracter classes in .cpp file (#535)

This is a workaround for a bug in GCC 4.4 failing to properly
encode inheritance info in the shared library when the class is
fully inlined.

Patch by Daniel Komisar <dkomisar@mak.com>

git-svn-id: http://svn.osgeo.org/geos/trunk@3960 5242fede-7e19-0410-aef8-94bd7d2200fb