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

--- a/tests/Makefile.am.orig	2019-06-03 15:46:16.380163423 -0400
+++ b/tests/Makefile.am	2019-06-03 15:46:26.099004417 -0400
@@ -8,7 +8,6 @@
 	cd benchmark && $(MAKE) $(AM_MAKEFLAGS) long_bench
 regtest:
 	cd regression && $(MAKE) $(AM_MAKEFLAGS) regtest
-	cd benchmark && $(MAKE) $(AM_MAKEFLAGS) regtest
 
 check-loop:
 	while [ 0 ]; do \