maintcheck: take advantage of some GNU make features We can do so now that our maintainer checks require GNU make unconditionally. * syntax-check.mk (ams, xtests): Redefine as "immediate variables", using the GNU make $(shell ...) builtin. (maintainer-check-list-of-tests): Take advantage of GNU make "-C" option. Don't use $(AM_MAKEFLAGS), we shouldn't need it with GNU make.