Sync with Git 2.15.2

* maint-2.15:
Git 2.15.2
Git 2.14.4
Git 2.13.7
verify_path: disallow symlinks in .gitmodules
update-index: stat updated files earlier
verify_dotfile: mention case-insensitivity in comment
verify_path: drop clever fallthrough
skip_prefix: add case-insensitive variant
is_{hfs,ntfs}_dotgitmodules: add tests
is_ntfs_dotgit: match other .git files
is_hfs_dotgit: match other .git files
is_ntfs_dotgit: use a size_t for traversing string
submodule-config: verify submodule names as paths

diff --cc apply.c
Simple merge

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

diff --cc builtin/update-index.c
Simple merge

diff --cc cache.h
index fd755c32cf5daf91115f6f534fdd9029609ee546,803bd7094a414eee9931746850011aae062b8976..4c29dd02e81ab5e5525c157657534b54cacae249
--- 1/cache.h
--- 2/cache.h
+++ b/cache.h
@@@ -646,16 -608,7 +646,16 @@@ extern int write_locked_index(struct in
  extern int discard_index(struct index_state *);
  extern void move_index_extensions(struct index_state *dst, struct index_state *src);
  extern int unmerged_index(const struct index_state *);
- extern int verify_path(const char *path);
 +
 +/**
 + * Returns 1 if the index differs from HEAD, 0 otherwise. When on an unborn
 + * branch, returns 1 if there are entries in the index, 0 otherwise. If an
 + * strbuf is provided, the space-separated list of files that differ will be
 + * appended to it.
 + */
 +extern int index_has_changes(struct strbuf *sb);
 +
+ extern int verify_path(const char *path, unsigned mode);
  extern int strcmp_offset(const char *s1, const char *s2, size_t *first_change);
  extern int index_dir_exists(struct index_state *istate, const char *name, int namelen);
  extern void adjust_dirname_case(struct index_state *istate, char *name);

diff --cc git-compat-util.h
Simple merge

diff --cc git-submodule.sh
Simple merge

diff --cc read-cache.c
Simple merge

diff --cc submodule-config.c
Simple merge

diff --cc submodule-config.h
Simple merge