Merge pull request #8821 from OSGeo/backport-8810-to-release/3.8

[Backport release/3.8] CMake: make GDAL_USE_LIBKML and GDAL_USE_OPENJPEG honor GDAL_USE_EXTERNAL_LIBS

cmake/helpers/CheckDependentLibraries.cmake

@@ -566,16 +566,7 @@ endfunction()
 gdal_check_package(SPATIALITE "Enable spatialite support for sqlite3" VERSION 4.1.2 CAN_DISABLE)
 gdal_check_package(RASTERLITE2 "Enable RasterLite2 support for sqlite3" VERSION 1.1.0 CAN_DISABLE)
 
-find_package(LibKML COMPONENTS DOM ENGINE)
-if (GDAL_USE_LIBKML)
-  if (NOT LibKML_FOUND)
-    message(FATAL_ERROR "Configured to use GDAL_USE_LIBKML, but not found")
-  endif ()
-endif ()
-cmake_dependent_option(GDAL_USE_LIBKML "Set ON to use LibKML" ON LibKML_FOUND OFF)
-if (GDAL_USE_LIBKML)
-  string(APPEND GDAL_IMPORT_DEPENDENCIES "find_dependency(LibKML COMPONENTS DOM ENGINE)\n")
-endif ()
+gdal_check_package(LibKML "Use LIBKML library" COMPONENTS DOM ENGINE CAN_DISABLE)
 
 define_find_package2(KEA libkea/KEACommon.h kea;libkea)
 gdal_check_package(KEA "Enable KEA driver" CAN_DISABLE)
@@ -742,7 +733,7 @@ if (GDAL_USE_OPENJPEG)
     message(FATAL_ERROR "Configured to use GDAL_USE_OPENJPEG, but not found")
   endif ()
 endif ()
-cmake_dependent_option(GDAL_USE_OPENJPEG "Set ON to use openjpeg" ON OPENJPEG_FOUND OFF)
+cmake_dependent_option(GDAL_USE_OPENJPEG "Set ON to use openjpeg" ${GDAL_USE_EXTERNAL_LIBS} OPENJPEG_FOUND OFF)
 if (GDAL_USE_OPENJPEG)
   string(APPEND GDAL_IMPORT_DEPENDENCIES "find_dependency(OpenJPEG MODULE)\n")
 endif ()