https://libspatialindex.org/
QGIS:https://github.com/qgis/QGIS/blob/master/cmake/FindSpatialindex.cmake
Question:http://osgeo-org.1560.x6.nabble.com/Config-fails-on-find-of-spatialindex-library-td4939392.html
SPATIALINDEX_LIBRARY Cmake
原文：https://www.cnblogs.com/2008nmj/p/10369717.html
