message: cmake: provide a compatibility target for users
  For users using older pugixml releases, add an ALIAS target which works
  with the new versions too.
diff: @PACKAGE_INIT@
  include("${CMAKE_CURRENT_LIST_DIR}/pugixml-targets.cmake")
  +
  +# If the user is not requiring 1.11 (either by explicitly requesting an older
  +# version or not requesting one at all), provide the old imported target name
  +# for compatibility.
  +if (NOT DEFINED PACKAGE_FIND_VERSION OR PACKAGE_FIND_VERSION VERSION_LESS "1.11")
  + add_library(pugixml ALIAS pugixml::pugixml)
  +endif ()
  