Merge branch 'cleanup/cmakemetafile' into 'master'

[cleanup][cmake] Remove CMAKE_METADATA_FILE.

See merge request core/dune-istl!479

python/CMakeLists.txt

@@ -2,7 +2,6 @@ add_subdirectory(dune)
 
 dune_python_install_package(
   PATH "."
-  CMAKE_METADATA_FILE dune/istl/metadata.cmake
   DEPENDS _istl
   CMAKE_METADATA_FLAGS DUNE_OPTS_FILE
 )