Add 'core.ignorecase' option

..and start using it for directory entry traversal (ie "git status" will
not consider entries that match an existing entry case-insensitively to
be a new file)

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -407,6 +407,7 @@ extern int delete_ref(const char *, const unsigned char *sha1);
 extern int trust_executable_bit;
 extern int quote_path_fully;
 extern int has_symlinks;
+extern int ignore_case;
 extern int assume_unchanged;
 extern int prefer_symlink_refs;
 extern int log_all_ref_updates;

config.c

@@ -342,6 +342,11 @@ int git_default_config(const char *var, const char *value)
 		return 0;
 	}
 
+	if (!strcmp(var, "core.ignorecase")) {
+		ignore_case = git_config_bool(var, value);
+		return 0;
+	}
+
 	if (!strcmp(var, "core.bare")) {
 		is_bare_repository_cfg = git_config_bool(var, value);
 		return 0;

dir.c

@@ -371,7 +371,7 @@ static struct dir_entry *dir_entry_new(const char *pathname, int len)
 
 struct dir_entry *dir_add_name(struct dir_struct *dir, const char *pathname, int len)
 {
-	if (cache_name_exists(pathname, len, 0))
+	if (cache_name_exists(pathname, len, ignore_case))
 		return NULL;
 
 	ALLOC_GROW(dir->entries, dir->nr+1, dir->alloc);

environment.c

@@ -14,6 +14,7 @@ char git_default_name[MAX_GITNAME];
 int trust_executable_bit = 1;
 int quote_path_fully = 1;
 int has_symlinks = 1;
+int ignore_case;
 int assume_unchanged;
 int prefer_symlink_refs;
 int is_bare_repository_cfg = -1; /* unspecified */