config: use home directory for `~` includes

Users can specify a config file to be included in the home directory
using `~/filename` syntax. Instead of looking in the global
configuration location (which may be overridden), use the user's
_actual_ home directory. This allows callers to change the global
configuration location separately from the home directory.

src/libgit2/config.c

@@ -860,7 +860,7 @@ static int git_config__parse_path(git_str *out, const char *value)
 			return -1;
 		}
 
-		return git_sysdir_expand_global_file(out, value[1] ? &value[2] : NULL);
+		return git_sysdir_expand_homedir_file(out, value[1] ? &value[2] : NULL);
 	}
 
 	return git_str_sets(out, value);

src/libgit2/config_file.c

@@ -528,7 +528,7 @@ static int included_path(git_str *out, const char *dir, const char *path)
 {
 	/* From the user's home */
 	if (path[0] == '~' && path[1] == '/')
-		return git_sysdir_expand_global_file(out, &path[1]);
+		return git_sysdir_expand_homedir_file(out, &path[1]);
 
 	return git_fs_path_join_unrooted(out, path, dir, NULL);
 }
@@ -616,7 +616,7 @@ static int do_match_gitdir(
 		git_fs_path_dirname_r(&pattern, cfg_file);
 		git_str_joinpath(&pattern, pattern.ptr, condition + 2);
 	} else if (condition[0] == '~' && git_fs_path_is_dirsep(condition[1]))
-		git_sysdir_expand_global_file(&pattern, condition + 1);
+		git_sysdir_expand_homedir_file(&pattern, condition + 1);
 	else if (!git_fs_path_is_absolute(condition))
 		git_str_joinpath(&pattern, "**", condition);
 	else