Use cabal for 'make bench'.

Makefile

@@ -57,10 +57,11 @@ ghcid-test: ## run ghcid/stack with tests
 	ghcid -c "stack repl --ghc-options=-XNoImplicitPrelude --flag 'pandoc:embed_data_files' --ghci-options=-fobject-code pandoc:lib pandoc:test-pandoc"
 
 bench: ## build and run benchmarks
-	stack bench \
-	  --ghc-options '$(GHCOPTS)' \
-	  --benchmark-arguments='$(BENCHARGS)' 2>&1 | \
-	  tee "bench_latest.txt"
+	cabal bench --benchmark-options='$(BENCHARGS)' 2>&1 | tee "bench_latest.txt"
+#	stack bench \
+#	  --ghc-options '$(GHCOPTS)' \
+#	  --benchmark-arguments='$(BENCHARGS)' 2>&1 | \
+#	  tee "bench_latest.txt"
 
 reformat: ## reformat with stylish-haskell
 	for f in $(SOURCEFILES); do echo $$f; stylish-haskell -i $$f ; done