Record dom-lt in spectral Makefile.

Otherwise it isn't run by default.

spectral/Makefile

@@ -3,7 +3,7 @@ include $(TOP)/mk/boilerplate.mk
 
 # TODO(michalt): Re-enable `secretary` (requires `random`)
 SUBDIRS = ansi atom awards banner boyer boyer2 calendar cichelli circsim \
-          clausify constraints cryptarithm1 cryptarithm2 cse eliza expert \
+          clausify constraints cryptarithm1 cryptarithm2 cse dom-lt eliza expert \
           exact-reals fft2 fibheaps fish gcd hartel integer knights lambda \
           last-piece lcss life mandel mandel2 mate minimax multiplier para \
           power pretty primetest puzzle rewrite scc simple sorting sphere \