Unify two free diskspace error messages

Although they won't be the same in the gettext catalog because of the '\n'
we should still use the same text.

Signed-off-by: Dan McGee <dan@archlinux.org>

lib/libalpm/error.c

@@ -58,7 +58,7 @@ const char SYMEXPORT *alpm_strerror(int err)
 		case PM_ERR_WRONG_ARGS:
 			return _("wrong or NULL argument passed");
 		case PM_ERR_DISK_SPACE:
-			return _("not enough disk space");
+			return _("not enough free disk space");
 		/* Interface */
 		case PM_ERR_HANDLE_NULL:
 			return _("library not initialized");