Log Message:
geography/geos: Update to 3.8.1

Changes in 3.8.1
2020-xx-xx

- Bug fixes / improvements
  - Stack allocate line segments in OverlapUnion (Paul Ramsey)
  - Avoid returning non-empty CoordinateSequence from empty Point
    (#1001, Dan Baston)
  - Avoid assertion failure with MSVC 2017 / 2019 (#1002, Dan Baston)
  - Remove whitespace from end of GEOSversion() output (azhi)
  - Improve performance of GEOSisValid (#1008, Dan Baston)
  - Avoid changing MultiLineString component order in GEOSReverse
    (#1013, Dan Baston)
  - Fix missing vtable for LineString and CoordinateArraySequenceFactory
    (#299 and #1016, Evgen Bodunov)
  - Reduce performance regression in GEOSBuffer (#1020)

Changes in 3.8.0
2019-10-10

- New things:
  - CAPI: GEOSBuildArea (#952, Even Rouault)
  - CAPI: GEOSMakeValid (#952, Even Rouault)
  - CAPI: GEOSPolygonize_valid (#727, Dan Baston)
  - CAPI: GEOSCoverageUnion (Dan Baston)
  - CAPI: GEOSCoordSeq_setXY, GEOSCoordSeq_setXYZ,
          GEOSCoordSeq_getXY, GEOSCoordSeq_getXYZ (Dan Baston)
  - CAPI: GEOSMinimumBoundingCircle (#735)
  - CAPI: GEOSGeom_createPointFromXY (Dan Baston)

- Improvements:
  - Improve overall performance by reducing of heap allocations (Dan Baston)
  - Improve performance and robustness of GEOSPointOnSurface (Martin Davis)
  - Improve performance of GEOSPolygonize for cases with many potential
    holes (#748, Dan Baston)
  - Support extended precision calculations (ttmath) and port JTS
    improvements related to extended precision (Paul Ramsey, Mateusz Loskot)
  - Improve performance of GEOSPolygonize for cases with many or complex
    shells (Dan Baston, Martin Davis)
  - Improve performance of Delaunay triangulations / Voronoi Diagrams
    (Dan Baston)
  - Improve performance of prepared geometry operations (Dan Baston)
  - Improve robustness of Delaunay triangulations (Paul Ramsey, Martin Davis)
  - Improve performance of unary union for lines (Dan Baston)
  - Improve general predicate, overlay, and buffer performance (Dan Baston, Paul \ 
Ramsey)
  - Improve cascaded union performance (Paul Ramsey, Martin Davis)
  - Allocate default GeometryFactory singleton on the stack (Sandro Mani)
  - Harmonize XML tests with JTS and harmonize cmake/autoconf
    test running (Paul Ramsey)
  - CMake modernization (Mateusz Loskot, Paul Ramsey, Dan Baston)
  - Return unique_ptr from most methods that produce a new geometry (Dan Baston)

- Changes:
  - Constructive geometry functions in CAPI now preserve SRID
    of input arguments in output (#896)