Merge branch 'bw/submodule-config-cleanup' into next

Code clean-up to avoid mixing values read from the .gitmodules file
and values read from the .git/config file.

* bw/submodule-config-cleanup:
submodule: remove gitmodules_config
unpack-trees: improve loading of .gitmodules
submodule-config: lazy-load a repository's .gitmodules file
submodule-config: move submodule-config functions to submodule-config.c
submodule-config: remove support for overlaying repository config
diff: stop allowing diff to have submodules configured in .git/config
submodule: remove submodule_config callback routine
unpack-trees: don't respect submodule.update
submodule: don't rely on overlayed config when setting diffopts
fetch: don't overlay config with submodule-config
submodule--helper: don't overlay config in update-clone
submodule--helper: don't overlay config in remote_submodule_branch
add, reset: ensure submodules can be added or reset
submodule: don't use submodule_from_name
t7411: check configuration parsing errors

diff --cc builtin/add.c
Simple merge

diff --cc builtin/checkout.c
Simple merge

diff --cc builtin/commit.c
Simple merge

diff --cc builtin/fetch.c
Simple merge

diff --cc builtin/grep.c
Simple merge

diff --cc builtin/ls-files.c
Simple merge

diff --cc builtin/reset.c
Simple merge

diff --cc builtin/submodule--helper.c
Simple merge

diff --cc diff.c
Simple merge

diff --cc submodule-config.c
Simple merge

diff --cc submodule.c
Simple merge

diff --cc submodule.h
Simple merge

diff --cc t/t7400-submodule-basic.sh
Simple merge

diff --cc unpack-trees.c
index 78590f1bfa7c895d3a269c6efe9114ddbb1b23eb,3c7f464faeb295102ee753e555d603e0ab14fc4b..68d34259c6cf6ecb4de29c32621ddbe967b6dbf9
--- 1/unpack-trees.c
--- 2/unpack-trees.c
+++ b/unpack-trees.c
@@@ -377,9 -367,8 +366,9 @@@ static int check_updates(struct unpack_
        remove_scheduled_dirs();
  
        if (should_update_submodules() && o->update && !o->dry_run)
-               reload_gitmodules_file(index, &state);
+               load_gitmodules_file(index, &state);
  
 +      enable_delayed_checkout(&state);
        for (i = 0; i < index->cache_nr; i++) {
                struct cache_entry *ce = index->cache[i];