Bump riscv-tools, to get some -mcmodel=medany fixes (#739)

.travis.yml

@@ -31,6 +31,7 @@ addons:
       - flex
       - texinfo
       - device-tree-compiler
+      - libusb-1.0-0-dev
 
 env:
   matrix:

regression/Makefile

@@ -133,6 +133,7 @@ $(RISCV)/install.stamp:
 	git -C $(abspath $(TOP))/riscv-tools submodule update --init --recursive riscv-opcodes
 	git -C $(abspath $(TOP))/riscv-tools submodule update --init --recursive riscv-pk
 	git -C $(abspath $(TOP))/riscv-tools submodule update --init --recursive riscv-tests
+	git -C $(abspath $(TOP))/riscv-tools submodule update --init --recursive riscv-openocd
 	+cd $(abspath $(TOP))/riscv-tools; RISCV=$(abspath $(RISCV)) ./build.sh
 	date > $@