Remove the benchmarks from the regtest target, they timeout on the buildds.

--- a/tests/benchmark/Makefile.am
+++ b/tests/benchmark/Makefile.am
@@ -229,13 +229,10 @@
 		done; \
 	fi
 
-.PHONY: short_bench long_bench regtest
+.PHONY: short_bench long_bench
 
 short_bench:
 	./run.sh short_bench_tests
 
 long_bench:
 	./run.sh long_bench_tests
-
-regtest:
-	./run.sh regression_tests
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -8,4 +8,3 @@
 	cd benchmark && $(MAKE) $(AM_MAKEFLAGS) long_bench
 regtest:
 	cd regression && $(MAKE) $(AM_MAKEFLAGS) regtest
-	cd benchmark && $(MAKE) $(AM_MAKEFLAGS) regtest