Do not initialize submodules from CMake

because any non-committed changes get lost upon reconfiguration.

CMakeLists.txt

@@ -22,10 +22,6 @@ dune_enable_all_packages()
 add_subdirectory(dune/perftool)
 add_subdirectory(cmake/modules)
 
-# Make sure that git submodules are correctly initialized
-execute_process(COMMAND git submodule update --init --recursive
-                WORKING_DIRECTORY ${CMAKE_SOURCE_DIR})
-
 # Add the python subdirectory to systematically install
 # the python dependencies there.
 add_subdirectory(python)