config.c: Remove unused git_config_global() function

Commit 8f323c00 (drop support for GIT_CONFIG_NOGLOBAL, 15-03-2011)
removed the git_config_global() function, among other things, since
it is no longer required. Unfortunately, this function has since
been unintentionally restored by a faulty conflict resolution.

Remove it.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -825,11 +825,6 @@ int git_config_system(void)
 	return !git_env_bool("GIT_CONFIG_NOSYSTEM", 0);
 }
 
-int git_config_global(void)
-{
-	return !git_env_bool("GIT_CONFIG_NOGLOBAL", 0);
-}
-
 int git_config_early(config_fn_t fn, void *data, const char *repo_config)
 {
 	int ret = 0, found = 0;