Merge pull request #21808 from luckeverda/fix/geocmakemain

fix: undo libgeos's setting of global CMAKE_CXX_STANDARD

contrib/CMakeLists.txt

@@ -507,6 +507,7 @@ if(${BUILD_GEOS})
     endif(${TD_LINUX})
     option(BUILD_SHARED_LIBS "Build GEOS with shared libraries" OFF)
     add_subdirectory(geos EXCLUDE_FROM_ALL)
+    unset(CMAKE_CXX_STANDARD CACHE) # undo libgeos's setting of global CMAKE_CXX_STANDARD
     target_include_directories(
         geos_c
         PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/geos/include>